Background

This is a group of aggressive lymphomas that have marked propensity to occur in the nose and paranasal sinuses. They are also known as angiocentric lymphomas and CD56 lymphomas. They are more common in men and peak during the 5th decade. Localized disease may be treated with irradiation with a 77% complete remission rate. In patients relapsing, disseminated disease may involve the skin, regional lymph nodes, lungs, and brain.

Under the microscope, these tumors are composed of a polymorphous mixture of inflammatory cells admixed with atypical lymphocytes having hyperchromatic, enlarged, and convoluted nuclei. These cells have a marked propensity to infiltrate large blood vessels. The identifying trait is found by immunohistochemistry which shows strong immunopositivity for CD56, a marker for natural killer (NK) cell differentiation. Natural killer cells comprise 10-15% of the normal circulating lymphocytes in the peripheral blood and play an important role in the immune system by lysing tumor cells without prior sensitization. These NK cells were once called null cells since they lack most of the usual T and B cell surface antigens.

CD56 is found in a small population of normal T cells. However, other T cell markers including T cell receptor gene rearrangement studies are negative. Epstein-Barr virus is reliably demonstrated indicating a primary pathogenic role for this virus.

OUTLINE

Epidemiology
Disease Associations
Pathogenesis
Laboratory/Radiologic/Other Diagnostic Testing
Gross Appearance and Clinical Variants
Histopathological Features and Variants
Special Stains/ Immunohistochemistry/ Electron Microscopy
Differential Diagnosis
Prognosis
Treatment
Commonly Used Terms
Internet Links

EPIDEMIOLOGY	CHARACTERISTIC
SYNONYMS	Sinonasal and extra-nasal NK/T-cell lymphoma
GEOGRAPHY	Common in Asia and South and Central America
Immunohistochemical and genetic analysis of Chinese nasal natural killer/T-cell lymphomas. Li T, Zhang B, Ye Y, Yin H. Department of Pathology, The First Hospital of Peking University, Beijing 100034, China.	Hum Pathol. 2006 Jan;37(1):54-60. Abstract quote   Nasal natural killer/T-cell lymphoma (N-NK/T-L) is prevalent in China. To further characterize this neoplasm, 36 cases of N-NK/T-L from 304 cases of malignant lymphomas in the north China area were investigated by histopathology, immunophenotyping, and genomic analysis of c-kit, in comparison with 11 cases of B-cell lymphoma (BCL) at the same region and 5 cases of nodal peripheral T-cell lymphoma (PTCL) (unspecified). Histopathologically, N-NK/T-L was characterized by coagulative necrosis, inflammatory background, and angiodestructive growth pattern. In 36 cases of N-NK/T-L, 27 cases (75.0%) were stained for CD45RO and 25 (72.2%) for CD3epsilon. Thirty cases (83.3%) were positive for T-cell intracellular antigen-1, 22 (61.1%) for granzyme B, 18 (50.0%) for CD56, and 11 (30.6%) for CD30, whereas none was positive for CD117. All 5 cases of PTCL displayed positive staining for CD45RO and T-cell intracellular antigen-1, 3 cases for CD3epsilon, but only 1 case for granzyme B. All 11 BCLs presented positive staining for CD20 and CD79a but negative for other antibodies. A significant relationship was observed between neoplastic cells pleomorphism and granzyme B expression (P < .05). Despite the fact that all cases were negative for CD117 staining, genomic sequences of c-kit 11 and exon 17 sequencing showed that 8 (26%) of 31 cases N-NK/T-L proved to contain genomic mutations, including 4 cases in exon 11 and 4 in exon 17. For the control group, only 1 (9%) of 11 BCLs and 1 (20%) of 5 cases of PTCL were detected to harbor mutations in exon 11. All mutations detected in 3 groups were missense by base substitution, and codes 571, 572, and 821 were hot spots. The results suggested that, in addition to histological features and routine immunophenotyping, granzyme B expression should be a more reliable marker in correct diagnosis of N-NK/T-L, and genetic analysis of c-kit mutation should be helpful in the diagnosis of this tumor.
Clinicopathologic and genotypic study of extranodal nasal-type natural killer/T-cell lymphoma and natural killer precursor lymphoma among Koreans. Ko YH, Ree HJ, Kim WS, Choi WH, Moon WS, Kim SW. Department of Diagnostic Pathology, Sungkyunkwan University School of Medicine, Samsung Medical Center, Seoul, Korea.	Cancer 2000 Nov 15;89(10):2106-16 Abstract quote BACKGROUND: This study aimed to define genotypic profile and to describe the clinicopathologic features of nasal-type natural killer (NK)/T-cell lymphoma of nasal and extranasal origin and NK precursor lymphoma. METHODS: NK/T-cell lymphomas from the upper aerodigestive tract (n = 45), skin (n = 2), gastrointestinal tract (n = 3), and soft tissue (n = 2) and NK precursor neoplasms (n = 3) were studied. Immunophenotype was analyzed by immunohistochemistry and flow cytometry. In situ hybridization with EBER 1/2 RNA probes was performed. T-Cell Receptor (TCR)-gamma gene rearrangement was analyzed by seminested polymerase chain reaction with heteroduplex analysis. Overall survival rate was correlated with clinicopathologic parameters and compared by Wilcoxon test. RESULTS: Clonal TCR-gamma gene rearrangement was detected in 3 of 31 upper aerodigestive and 1 of 2 skin tumors. When immunostained using paraffin embedded tissue, 6 upper aerodigestive lymphomas were negative for CD56 in which 4 cases lacked clonal TCR gene rearrangement. Epstein-Barr virus (EBV) mRNA was detected in 33 upper aerodigestive tumors including 26 of 29 nasal tumors (90%), and 7 of 10 extranasal tumors (70%). There was no histologic, immunophenotypic, or genotypic differences according to the lineage and EBV association in upper aerodigestive lymphomas. Among the patients with upper aerodigestive tumors, overall 1-year survival rate was 41%, and correlated well with the stage (P < 0.05) but not with the size of tumor cells, EBV status, and lineage (P > 0.05). Median survival rate of lymphomas from other sites excluding upper aerodigestive tract was not significantly different from that of upper aerodigestive lymphomas with same stage (P > 0.05). Unlike nasal-type NK/T-cell lymphomas, NK precursor lymphoma involved the bone marrow and lymph nodes at initial presentation or in the course of disease. Tumor cells were positive for TdT in all and myeloid markers in two. TCR gene rearrangement was germ line. CONCLUSIONS: Most upper aerodigestive nasal-type NK/T-cell lymphomas among Koreans are genotypically of NK derivation and few belong to T lineage. Presence or absence of EBV has no significant correlation with the histologic changes and the lineage of these lymphomas.
Sinonasal NK/T-cell Lymphomas in the United States Karl Gaal, M.D.; Nora C. J. Sun, M.D.; Antonio M. Hernandez, M.D.; Daniel A. Arber, M.D. From the Departments of Pathology at City of Hope National Medical Center, Duarte, California, (K.G., D.A.A.), Harbor UCLA Medical Center, Torrance, California (N.C.J.S.), and Kaiser Permanente, Los Angeles, California, U.S.A. (A.M.H.).	Am J Surg Pathol 2000;24:1511-1517 Abstract quote Sinonasal natural killer (NK)/T-cell lymphomas are common in Asia and areas of South and Central America but are rarely seen in the United States, where they have not been as well characterized. Fifteen cases diagnosed in Southern California were studied with respect to histologic features, immunophenotype, Epstein-Barr virus EBER in-situ hybridization (EBV EBER-ISH), and T-cell receptor gamma chain (TCR-) gene rearrangement. Although ethnic background was available for only seven patients, six were of Asian or Hispanic descent with only one non-Hispanic white known. Twelve presented as sinonasal lesions, but three were limited to the oropharynx. Most cases (11 of 15) demonstrated both necrosis and an angiodestructive pattern. All cases demonstrated cytoplasmic CD3 positivity (15 of 15), and were positive for both TIA-1 and granzyme B (14 of 14). Perforin was positive in 5 of 14. CD56 was expressed in 10 of 15 and CD8 in 3 of 15. EBV EBER-ISH was positive in 14 of 14 and TCR- gene rearrangement was detected in 1 of 14 cases. None (0 of 14) were positive for CD16 or CD57. Although CD16-positive histiocytes were abundant, double-label EBER-ISH/IHC failed to identify CD16 expression on EBV-positive tumor cells. Three cases with pleomorphic large cell morphology showed focal CD30 positivity, raising the differential diagnosis of anaplastic large cell lymphoma, but all were ALK-1-negative and otherwise similar to the other cases of NK/T-cell lymphoma. Sinonasal NK/T-cell lymphomas in the United States most often occur in ethnic groups from areas of reported high frequency (Asia, Central and South America), although less commonly than in endemic populations, and are otherwise similar phenotypically. A combined approach, including immunohistochemistry, EBV EBER-ISH, and TCR gene rearrangement studies, is most helpful to arrive at the correct diagnosis.

 

PATHOGENESIS	CHARACTERIZATION
GENERAL
'Agranular CD4+ CD56+ hematodermic neoplasm' (blastic NK-cell lymphoma) originates from a population of CD56+ precursor cells related to plasmacytoid monocytes. Petrella T, Comeau MR, Maynadie M, Couillault G, De Muret A, Maliszewski CR, Dalac S, Durlach A, Galibert L. Centre de Pathologie of Dijon and the Department of Pathology, Dijon University Hospital, France.	Am J Surg Pathol 2002 Jul;26(7):852-62 Abstract quote In 1999, we reported seven cases of an unusual hematologic malignancy with primary cutaneous presentation that appeared as a distinct clinicopathologic entity characterized by medium-sized tumor cells with a peculiar CD3- CD4+ CD56+ CD43+ HLA-DR+ cell surface phenotype. Because the origin of tumor cells was not clear and they exhibited a nonlineage-specific phenotype, we hypothesized that such tumors likely originated from hematologic-myeloid precursor cells and were tentatively assigned the designation "agranular CD4+ CD56+ hematodermic neoplasms." In the present study we report 14 cases (seven already reported and seven additional cases) of these tumors, and simultaneously we present now a rare population of cells that we have identified in the peripheral blood of healthy volunteers treated with Flt3 ligand. These cells express all the characteristic markers of CD4+ CD56+ hematodermic neoplasms. This population appears to be related to plasmacytoid monocytes because they also expressed CD68 and bright levels of CD123. To confirm the relationship between these normal cells and CD4+ CD56+ hematodermic neoplasms, we conducted an extensive comparative phenotypic study. Results show that these two cell types are indeed related because they share many phenotypic features, including the presence of CD4, CD56, CD43, CD68, and HLA-DR and the absence of other T, B, NK, or myelomonocytic markers. More importantly, we found that the bright expression of CD123 by immunohistochemistry is a distinctive characteristic of CD4+ CD56+ hematodermic neoplasms because all (n = 14) cases expressed this marker, whereas only two specimens in a control panel comprising 30 samples of related tumors expressed comparable levels of CD123. We therefore propose that oncogenic transformation of NCAM-expressing plasmacytoid monocyte-like cells may lead to "agranular CD4+ CD56+ hematodermic neoplasm."
CHROMOSOMAL ABNORMALITIES
Aggressive NK cell lymphoma/leukemia with clonal der(3)t(1;3) (q12;p25), del(6)(q13) and del(13)(q12q14). Hamaguchi H, Yamaguchi M, Nagata K, Koike E, Imagunbai M, Tsurukubo Y, Yamamoto K. Department of Hematology, Musashino Red Cross Hospital, 1-26-1 Kyonan-cho, Musashino, 180-8610, Tokyo, Japan	Cancer Genet Cytogenet 2001 Oct 15;130(2):150-4 Abstract quote We describe a 54-year-old man with CD2, CD7, and CD56-positive but CD3, CD4, and CD8-negative aggressive NK cell lymphoma/leukemia. Chromosome analysis of the peripheral blood cells showed clonal aberration consisting of 46,XY,dup(3)(p21p25),der(3)t(1;3)(q12;p25),del(5)(q13q22), del(6)(q13),del(13)(q12q14). The peripheral blood lymphoma cells contained clonal EBV-DNA by Southern blot analysis. The disease was refractory to chemotherapy and the clinical course was aggressive and rapid. Deletion 6q and deletion 13q have been frequently reported in NK cell lymphoma/leukemia. Thus, some tumor suppressor genes involving NK cell malignancies may be present in these regions.
CYTOTOXIC MARKERS
Differential expression of cytotoxic molecules and killer cell inhibitory receptors in CD8+ and CD56+ cutaneous lymphomas. Kamarashev J, Burg G, Mingari MC, Kempf W, Hofbauer G, Dummer R. Department of Dermatology, University Hospital, Zurich, Switzerland.	Am J Pathol 2001 May;158(5):1593-8 Abstract quote Cutaneous lymphomas of the cytotoxic phenotype, including CD8+ and CD56+ lymphomas, have only recently been recognized. To characterize the phenotypic profile of these lymphomas, we investigated the expression of both cytotoxic molecules and killer cell inhibitory receptors by immunohistochemistry techniques. Frozen sections from four CD8+ and from three CD56+ cutaneous lymphomas were stained for the cytotoxicity markers including T-cell restricted intracellular antigen-1, perforin, granzyme B, and for expression of the inhibitory receptors including p58.1, p58.2, p70, p140, CD94, NKG2, and leukocyte immunoglobulin-like receptor (LIR-1). Apart from LIR-1, the CD8+ lymphomas in our series express p70 and p140 from the inhibitory receptors and only one or two of the cytotoxic proteins. The CD56+ lymphomas, on the other hand, express only LIR-1 of the set of inhibitory receptors and the whole panel of cytotoxic antigens. Various subtypes of cytotoxic cutaneous lymphomas (CD8+ and CD56+) differ in regard to their phenotypic and functional profile, which may explain differences in their biological behavior.
TUMOR SUPPRESSOR GENES
Molecular Analysis of Tumor Suppressor Genes, Rb, p53, p16INK4A, p15INK4B and p14ARF in Natural Killer Cell Neoplasms. Sakajiri S, Kawamata N, Egashira M, Mori K, Oshimi K. Division of Hematology, Department of Medicine, Juntendo University School of Medicine, Bunkyo-ku, Tokyo 113-8421, Japan.	Jpn J Cancer Res 2001 Oct;92(10):1048-1056 Abstract quote Natural killer (NK) cell neoplasms, which are derived from mature or precursor NK cells, are rare diseases and are observed predominantly in Asian countries. We analyzed the status of the Rb, p53, p15INK4B, p16INK4A and p14ARF genes in these diseases by Southern blot, polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and western blot analysis. We used 31 NK cell neoplasms, including four cell lines derived from NK cell neoplasms, 3 myeloid / NK cell precursor acute leukemias, 4 blastic NK cell lymphoma / leukemias, 4 aggressive NK cell leukemia / lymphomas, 4 nasal NK cell lymphomas, and 12 chronic NK lymphocytosis. We found gene amplification of the p53 gene in one nasal NK cell lymphoma, and point mutations of the p53 gene in one blastic NK cell lymphoma / leukemia and one chronic NK lymphocytosis. In addition, homozygous deletions of p15, p16 and p14 genes in 5 out of 31 samples were detected; 3 were from nasal NK cell lymphoma and 2 from blastic NK cell lymphoma / leukemia. Also hemizygous deletion of the Rb gene in one blastic NK cell lymphoma was detected. Rb proteins were highly expressed in one cell line as well as two myeloid / NK cell precursor acute leukemias. In other cell lines, complete loss and an aberrant migration pattern of Rb protein expression were observed. Comparative genomic hybridization suggested that the homozygous deletions of the p15, p16 and p14 were subtle chromosomal deletions and could not be identified by standard karyotyping in some cases. Although the number of cases we analyzed was not large, alterations identified in the Rb, p53, p16, p15 and p14 genes are of significance and might be associated with tumorigenesis in NK cell neoplasms.
Expression of cytotoxic proteins in peripheral T-cell and natural killer-cell (NK) lymphomas: association with extranodal site, NK or Tgammadelta phenotype, anaplastic morphology and CD30 expression. Kanavaros P, Boulland ML, Petit B, Arnulf B, Gaulard P. Department of Pathology, Henri Mondor Hospital AP-HP, Creteil, France.	Leuk Lymphoma 2000 Jul;38(3-4):317-26 Abstract quote Most peripheral T-cell lymphomas (PTCL) express the alphabeta T-cell receptor (TCR) whereas rare PTCL express the gammadelta TCR. Most if not all gammadelta PTCL are extranodal lymphomas and among them, hepatosplenic gammadelta PTCL constitute a distinct clinicopathological entity. Besides alphabeta and gammadelta PTCL, there is a recently recognized group of extranodal, mainly nasal tumours, which display, in most instances, phenotypic and genotypic features of Natural-Killer cell non-Hodgkin's lymphomas (NK-NHL). Cytotoxic cells, including NK cells and cytotoxic alphabeta and gammadelta T lymphocytes may induce lysis of the target by using granule-associated cytotoxic proteins such as the T-cell intracellular antigen-1 (TIA-1), perforin and granzyme B. Expression of TIA-1 can be detected in all cytotoxic cells whereas granzyme B and perforin expression can be detected in high levels only in activated cytotoxic cells. Recently, several studies showed that the expression of these cytotoxic proteins in tumour cells of PTCL and NK-NHL is associated with a) extranodal site of clinicopathological presentation b) NK or Tgammadelta-cell phenotype c) CD30 expression in cutaneous T-cell lymphoproliferations and d) anaplastic morphology in nodal PTCL. This latter finding contrasts with the data that only rare Hodgkin lymphomas (HL) express cytotoxic proteins in Hodgkin and Reed-Sternberg cells. Altogether the data of the literature indicate that most extranodal T and NK-NHL are activated cytotoxic lymphomas with the notable exception of hepatosplenic gammadelta PTCL which represent tumours of non-activated cytotoxic cells. On this basis, it is suggested that the expression of cytotoxic proteins may be useful for the identification and classification of extranodal T and NK-cell lymphomas and, to some extent, for the differential diagnosis between HL and CD30+ anaplastic large cell lymphomas. Cytotoxic lymphomas are preferentially localized in extranodal sites such as skin, lung, upper respiratory and gastrointestinal tracts, which are continuously exposed to various antigens. Since cytotoxic T and NK cells are regarded as first line of defense in these sites, and some cytotoxic tumours such as nasal lymphomas and enteropathy-type intestinal lymphomas are associated with EBV and gliadin, respectively, it is likely that chronic antigen exposure may play a role in the pathogenesis of cytotoxic lymphomas occurring in mucosa and/or skin. Besides chronic antigenic stimulation, chronic immunosuppression may also have pathogenetic significance in cytotoxic lymphomas in view of their increased incidence in immunocompromised patients.
p53
Expression of p53 protein in T- and natural killer-cell lymphomas is associated with some clinicopathologic entities but rarely related to p53 mutations	Hum Pathol 2001:32:196-204 51 cases of these lymphomas for the expression of p53 and its relationship with p53 gene mutations, the expression of the p21 protein as well as the proliferative and apoptotic indices Overexpression of p53 was found in 19 cases (37%), whereas mutations of the p53 gene were observed in only 5 of 28 tested cases Anaplastic large cell lymphomas showed a frequent overexpression of p53 (7/8 cases) and p21 (6/8 cases) proteins and rare p53 mutations (1/7 cases) Nodal peripheral T-cell lymphomas unspecified showed relatively frequent overexpression of p53 protein (5/7 cases), infrequent p21 expression (2/7 cases), and rare p53 gene mutations (1/6 cases) Angioimmunoblastic lymphomas, the common phenotype was p53–/p21– (15/17 cases), with only a few scattered p53-positive cells, which, on the basis of double staining results, were mostly Epstein-Barr virus-infected B cells. A p53 gene mutation was only found in 1 case (1/8 cases) of angioimmunoblastic lymphoma, Mycosis fungoides showed p53 overexpression in 2 of 4 cases, including 1 case with p53 gene mutation and features of cytologic tumor progression Nasal NK/T lymphomas showed p53 overexpression in 2 of 5 cases, 1 of which had a p53 gene mutation All lymphoblastic T-cell lymphomas (5 cases) and hepatosplenic T-cell lymphomas (3 cases) were negative for expression of p53 and p21 proteins. Conclusion: p53 protein overexpression is a common finding in some entities of T- and T/NK-cell lymphomas, whereas a p53 gene mutation is a rare, sporadic, and rather late event associated with tumor progression in some instances p53/p21 expression pattern appears to be variable in T- and T/NK-cell lymphoma entities, reinforcing the concept of distinct, entity-related mechanisms of pathogenesis in these tumors

 

LABORATORY/ RADIOLOGIC	CHARACTERIZATION
RADIOLOGIC
Nasal T-cell/natural killer cell lymphoma: CT and MR imaging features of a new clinicopathologic entity. Ooi GC, Chim CS, Liang R, Tsang KW, Kwong YL. Department of Diagnostic Radiology, The University of Hong Kong, Queen Mary Hospital, Pokfulam, China.	AJR Am J Roentgenol 2000 Apr;174(4):1141-5 Abstract quote OBJECTIVE: Nasal T-cell/natural killer cell lymphoma is a new clinicopathologic entity with a characteristic immunophenotypic profile and distinct clinical features. This study describes the radiologic features of nine cases of proven nasal T-cell/natural killer cell lymphoma. CONCLUSION: Nasal T-cell/natural killer cell lymphoma is often a locally destructive (T stages 3 and 4) disease, typically presenting with obliteration of the nasal passages and maxillary sinuses. Involvement of the adjacent alveolar bone, hard palate, orbits, and nasopharynx is found in more than 50% of cases and is associated with extensive soft-tissue masses. Presence of bone erosion is suggestive but not diagnostic of the disease.

 

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
GENERAL	Divided into nasal type and extranasal type Extranasal tumor usually present at high stage with systemic symptoms common
EXTRANODAL- GENERAL
Nasal-type extranodal natural killer/T-cell lymphomas: a clinicopathologic and genotypic study of 42 cases in Singapore. Ng SB, Lai KW, Murugaya S, Lee KM, Loong SL, Fook-Chong S, Tao M, Sng I. Department of Pathology, Singapore General Hospital, Singapore.	Mod Pathol. 2004 Sep;17(9):1097-107. Abstract quote   We studied the clinicopathologic features of 42 cases of nasal-type extranodal natural killer (NK)/T-cell lymphoma in Singapore and compared our findings with other series reported in the Asian and Western populations. A panel of immunohistochemical stains, which included CD2, CD3, CD4, CD8, CD56, T-cell intracellular Antigen-1 and granzyme B, and in situ hybridization for Epstein-Barr virus encoded RNA (EBER) were performed. Polymerase chain reaction for T-cell receptor-gamma gene rearrangement using both gel and capillary electrophoresis were evaluated to determine the proportion of tumors which are of true T-cell lineage. We also studied the functional status of the overexpressed p53 protein in these lymphomas by correlating p53 expression with its downstream target protein, p21. In all, 31 out of 42 cases presented in the upper aerodigestive tract. The other sites of involvement included gastrointestinal tract, skin, soft tissue, testis, liver, spleen, bone marrow and brain. The tumors displayed characteristic morphologic features. In situ hybridization for EBER was detected in 41 out of 42 cases (97.6%). The only significant adverse prognostic factor identified was an International Prognostic Index of two or more. A significantly higher proportion of the tumors (27%), compared to previous studies, demonstrated monoclonal T-cell receptor-gamma gene rearrangement. There was, however, no difference in survival or clinicopathologic features between the true NK-cell tumors and their T-cell counterparts. Overexpression of p53 was present in 40% of the cases, but no significant difference in survival rate was detected in patients with p53 overexpression and there was no association between p53 overexpression with large cell morphology, and advanced stage of disease. These findings suggest that molecular aberrations other than those of the p53 pathway may be operative in the pathogenesis of this malignancy.
BREAST
EBV-associated, extranodal NK-cell lymphoma, nasal type of the breast, after heart transplantation. Tsao L, Draoua HY, Mansukhani M, Bhagat G, Alobeid B. 1Department of Pathology, Columbia University, New York, NY, USA.	Mod Pathol. 2004 Jan;17(1):125-30. Abstract quote   Post-transplantation lymphoproliferative disorders (PTLDs) are predominantly Epstein-Barr virus (EBV)-associated B-cell lymphoproliferations. PTLDs of T-cell lineage are rare, mostly reported after renal transplantation and show less frequent association with EBV. NK-cell lymphomas after transplantation (NK-cell PTLDs) are very rare; only five cases are reported so far in the English literature, all developed after renal transplantation. We describe a case of EBV-associated, extranodal NK-cell lymphoma of nasal type, involving the breast in a cardiac allograft recipient 5 years after transplantation. The neoplastic cells are positive for CD2, cytoplasmic CD3, CD7, CD43, CD56, TIA-1 and p53; and negative for surface CD3 and CD57. Analysis of T-cell receptor beta and gamma genes fails to show clonal rearrangement. EBV studies show clonal episomal integration of EBV and latency II pattern (EBER-1+, LMP-1+, EBNA-1+, EBNA-2-). In conclusion, NK-cell PTLDs are rare complications that arise relatively late after solid organ transplantation, show strong association with EBV, and can follow an aggressive clinical course. To the best of our knowledge, we present the first reported case of NK-cell PTLD after cardiac transplantation and the unifying clinical and diagnostic features of NK-cell PTLDs occurring after solid organ transplantation.
INTESTINAL
An unusual case of peripheral T-cell lymphoma with CD56 positivity and angiocentric, angiodestructive morphology arising in the ileum. Frank MC, Bono E, Sun T. Department of Pathology, University of Colorado Health Sciences Center, Denver, CO 80262, USA.	Arch Pathol Lab Med. 2005 Apr;129(4):527-30. Abstract quote   Natural killer cell and cytotoxic T-cell lymphomas are frequently difficult to distinguish because they share many common features, and yet it is important to make an accurate diagnosis because their prognoses differ. We report an unusual case of a white man with a CD56-positive T-cell lymphoma in the ileum. The histologic pattern was characterized by angioinvasion and angiodestruction. Immunohistochemical staining showed positive reactions to CD3, CD8, CD43, CD45RO, CD56, and T-cell intracellular antigen-1, but negative reactions to CD4, CD5, CD20, CD23, and CD57. Epstein-Barr virus (EBV) was not detected by EBV-latent membrane protein staining and EBV polymerase chain reaction technique. The T-cell receptor gamma chain gene was rearranged. According to the World Health Organization classification, the absence of EBV excludes the diagnosis of extranodal natural killer/T-cell lymphoma, nasal type. However, the association of EBV with this lymphoma in white patients is not clear. Therefore, absence of EBV alone does not necessarily exclude nasal-type natural killer/T-cell lymphoma, particularly because the histologic pattern in this case is highly characteristic of this tumor.
Gastrointestinal T cell lymphoma: predominant cytotoxic phenotypes, including alpha/beta, gamma/delta T cell and natural killer cells. Katoh A, Ohshima K, Kanda M, Haraoka S, Sugihara M, Suzumiya J, Kawasaki C, Shimazaki K, Ikeda S, Kikuchi M. First Department of Pathology, School of Medicine, Fukuoka University, Japan.	Leuk Lymphoma 2000 Sep;39(1-2):97-111 Abstract quote Gastrointestinal T cell lymphoma (TCL) is a rare subset of peripheral TCL, presenting with or without cytotoxic phenotype, a history of coeliac disease (CD) and enteropathy. However, CD is rare in Japan. Here, we describe the clinicopathological features of 18 Japanese cases. Lesions were found in the small intestine (n=13), stomach (n=3) and colon (n=2). Seven patients presented with enteropathy but none had a history of CD. Lymphomas appeared as ulceration (n=11), tumour formation (n=6), or polypoid growth (n=1). Histologically (REAL classification), neoplastic lesions were composed of intestinal type T cell lymphoma (ITCL, n=13, including one case with NK type), anaplastic large cell (ALCL, n=2), adult T cell leukaemia/lymphoma (ATLL, n=2), and lymphoblastic type (n=1). Epstein Barr virus infection was detected by EBER-1 in situ hybridization in 6 of 11 cases with ITCL but not in the other types. ALCL expressed CD30. CD56 was expressed in 3 of 11 cases of ITCL but not in other types. Among the 10 examined cases, 8 were alphabeta T cell type [CD2+, CD3+, T cell receptor (TCR)delta-1-, betaF1+], one was gammadelta T cell type [CD2+, CD3+, TCRdelta-1+, betaF1-], and the remaining case expressed natural killer (NK) cell type [CD2+, CD3-, CD56+, TCRdelta-1-, betaF1-]. Among the 8 examined cases, 3 expressed CD103 molecule, which was associated with extrathymic T cells of intraepithelial lymphocytes. All cases except ATLL expressed the cytotoxicity-associated molecule of TIA-1, and 11 of 14 TIA-1 positive cases expressed activated cytotoxic molecules of perforin, granzyme B, and/or Fas ligand. Despite the morphological, genetic and phenotypic heterogeneity, prognosis was poor, and 11 of 13 patients with small intestinal lesions died albeit appropriate treatment, but 3 of 4 patients with gastric or colonic lesions were still alive. The main cause of death was intestinal perforation. The latter might be due to the site specificity of small intestine and tumour cytotoxicity.
Expression of killer cell inhibitory receptors is restricted to true NK cell lymphomas and a subset of intestinal enteropathy-type T cell lymphomas with a cytotoxic phenotype. Dukers DF, Vermeer MH, Jaspars LH, Sander CA, Flaig MJ, Vos W, Willemze R, Meijer CJ. Department of Pathology, Vrije Universiteit, Amsterdam, The Netherlands.	J Clin Pathol 2001 Mar;54(3):224-8 Abstract quote BACKGROUND/AIMS: Killer inhibitory receptors (KIR) have a modulating effect on the cytotoxic functions of natural killer (NK) cells and T cells. Because lymphoma cells often have the same receptors as their non-neoplastic counterparts, this study investigated the expression of KIR on well defined groups of NK and T cell lymphomas, with and without a cytotoxic phenotype, from different sites of origin. METHODS: Nine CD56+/CD3- NK cell lymphomas, 29 CD3+/CD56- T cell lymphomas with a cytotoxic phenotype, and 19 T cell lymphomas without a cytotoxic phenotype were stained for KIR using monoclonal antibodies specific for CD94, CD158a, and CD158b. In addition, the expression of KIR was studied on normal lymphoid tissues. RESULTS: KIR expression was seen in five of nine true NK cell lymphomas including three of four nasal, one of four cutaneous, and one of one intestinal lymphoma nasal type. Double staining for CD56 and CD94 in normal lymphoid tissues revealed that KIR was predominantly expressed by CD56+ NK cells and sporadically on CD8+ T cells. Moreover, enteropathy-type T cell lymphomas with a cytotoxic phenotype showed KIR expression (three cases expressing CD94 and one case expressing CD158a). All nodal and extranodal nonintestinal T cell lymphomas with or without a cytotoxic phenotype lacked expression of KIR. CONCLUSIONS: These results show that KIR expression is restricted to CD56+/CD3- true NK cell lymphomas originating from the nose, gut, and skin, as well as in a subset of extranodal T cell lymphomas originating from the small intestine, which possessed a cytotoxic phenotype. Thus, the presence of KIR on NK/T cell lymphomas seems to mimic the distribution of KIR found on NK and T cells in normal lymphoid tissue.
Primary CD56 positive lymphomas of the gastrointestinal tract. Chim CS, Au WY, Shek TW, Ho J, Choy C, Ma SK, Tung HM, Liang R, Kwong YL. Department of Medicine, Queen Mary Hospital, University of Hong Kong, Hong Kong, China.	Cancer 2001 Feb 1;91(3):525-33 Abstract quote BACKGROUND: Primary CD56 positive lymphoma of the gastrointestinal (GI) tract is rare. Genotypically, these tumors can be classified into natural killer (NK)-like T-cell lymphoma or NK cell lymphoma by the presence or absence of T-cell receptor (TCR) gene rearrangement. However, they have a considerable degree of morphologic and immunophenotypic overlap, making a definitive diagnosis difficult. METHODS: The clinicopathologic features of three patients with primary CD56 positive lymphoma of the small and large bowel are presented. This is followed by a review of the English literature from 1966 to the present. RESULTS: All patients had CD56 positive/CD3epsilon positive disease on paraffin section. Two patients were positive for Epstein-Barr virus-encoded early nuclear RNAs (EBER) according to in situ histochemistry results and were negative for TCR gene rearrangement, consistent with primary NK lymphoma of the GI tract. The other patient was EBER negative with rearranged TCR, consistent with NK-like T-cell lymphoma. There was no clinical or histologic evidence of enteropathy in any of the patients. The major presenting symptoms included fever, weight loss, and intestinal perforation. All patients died between 1 week and 6 months after diagnosis despite undergoing surgery and intensive chemotherapy. CONCLUSIONS: These results, together with a literature review, suggest that primary NK cell lymphoma of the GI tract may be considered a distinct clinicopathologic entity. Both primary NK and NK-like T-cell lymphoma pursue an aggressive clinical course. EBER and TCR gene rearrangement are useful in distinguishing NK cell lymphoma from NK-like T-cell lymphoma, particularly when frozen tissue is not available for immunophenotyping.
POST-TRANSPLANT
Nasal natural killer cell lymphoma in a post-renal transplant patient. Mukai HY, Kojima H, Suzukawa K, Hori M, Komeno T, Hasegawa Y, Ninomiya H, Mori N, Nagasawa T. Division of Hematology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.	Transplantation 2000 Apr 15;69(7):1501-3 Abstract quote Posttransplant lymphoproliferative disorders in organ allograft recipients are most commonly of B-cell origin and only occasionally of T-cell origin. We present here a case of nasal natural killer cell lymphoma associated with Epstein-Barr virus that occurred in a recipient of a renal transplant 4 years posttransplantation. Immunohistochemically, the lymphoma cells showed CD2-, surface CD3-, cytoplasmic CD3E+, CD56+, CD57-, CD16-, and CD43+ phenotype. Analyses of T-cell receptor beta and gamma genes showed germ line configurations. EBER-1 was detectable in the lymphoma cells. The patient was diagnosed as having natural killer cell lymphoma and was treated with six courses of combination chemotherapy for non-Hodgkin's lymphoma He has been in remission for more than 3 years thereafter. To the best of our knowledge, this is the first report of a posttransplant NK cell lymphoma associated with Epstein-Barr virus.
Epstein-Barr virus–associated extranodal NK/T-cell lymphoma, nasal type of the hypopharynx, in a renal allograft recipient: Case report and review of literature Sylvia Stadlmann, MD Falko Fend, MD Patrizia Moser, MD Peter Obrist, MD Richard Greil, MD Stephan Dirnhofer, MD	Hum Pathol 2001;32:1264-1268. Abstract quote Posttransplant lymphoproliferative disorders (PTLPDs) are predominantly B-cell lymphoproliferations, whereas a T-cell origin is rarely observed. In contrast to B-cell PTLPD, T-cell PTLPDs show an inconsistent association with Epstein-Barr virus (EBV). Until now, only 13 cases of EBV-associated T-cell PTLPDs have been reported. We describe a case of an EBV-associated T-cell PTLPD in a renal allograft recipient 2 years after transplantation. Histologic examination showed medium- to large-sized lymphoid cells with an angiocentric growth pattern and necrosis. The atypical cells showed a CD2+, CD3+, CD7+, CD43+, CD45R0+, CD56+, and CD4–, CD5–, CD8– F1- phenotype with expression of the latent membrane protein (LMP)-1 of EBV. In addition, EBV-specific RNAs (EBER 1/2) were identified by in situ hybridization. Molecular analysis of the T-cell receptor (TCR) chain by polymerase chain reaction (PCR) showed a polyclonal pattern. The morphologic, immunohistochemical, and molecular findings were consistent with a diagnosis of an EBV-associated extranodal natural killer (NK)/T-cell non-Hodgkin lymphoma (NHL) of nasal type. To our knowledge, this is the first reported case of this rare entity in the posttransplant setting.
SALIVARY GLAND
Natural Killer-like T-Cell Lymphoma of the Parotid in a Patient Infected With Human Immunodeficiency Virus. Cornfield DB, Papiez JS, Lynch JT, Rimsza LM. Departments of Pathology, Immunology, and Laboratory Medicine (Drs Cornfield, Papiez, and Rimsza) and Medicine (Dr Lynch), University of Florida College of Medicine, Gainesville. Dr Cornfield is now with the Department of Pathology, Lehigh Valley Hospital, Allentown, Pa.	Arch Pathol Lab Med 2002 Jun;126(6):738-741 Abstract quote A 42-year-old man with acquired immunodeficiency syndrome developed a mass of the right parotid gland and multiple hepatic masses. Hematoxylin-eosin-stained sections of the parotid lesion showed a diffuse infiltrate of large mononuclear cells with vesicular nuclei and prominent nucleoli, consistent with a non-Hodgkin lymphoma. Immunohistochemical stains demonstrated expression of the T-cell markers CD3 and UCHL-1, as well as latent membrane protein 1 and T-cell intracellular antigen 1. Flow cytometry showed surface expression of CD2, CD3, CD7 (dim), CD8, and CD56. CD5 was not expressed. Molecular evaluation by polymerase chain reaction demonstrated monoclonal rearrangement of the T-cell receptor gamma gene. Epstein-Barr virus early RNA and human immunodeficiency virus RNA were demonstrated by in situ hybridization. To our knowledge, this is the first reported case of T-cell lymphoma of the parotid in a patient infected with human immunodeficiency virus. After 2 separate chemotherapy regimens, the patient achieved clinical remission for 1(1/2) years; he then developed progressive pulmonary lesions and died.
SKIN
Subcutaneous, blastic natural killer (NK), NK/T-cell, and other cytotoxic lymphomas of the skin: a morphologic, immunophenotypic, and molecular study of 50 patients. Massone C, Chott A, Metze D, Kerl K, Citarella L, Vale E, Kerl H, Cerroni L. Department of Dermatology, University of Graz, Austria.	Am J Surg Pathol. 2004 Jun;28(6):719-35. Abstract quote   A new group of subcutaneous, natural killer (NK), NK/T-cell, and other cytotoxic T-cell lymphomas of the skin has been recently described, and some have been included as distinct clinicopathologic entities in the classification of hematologic malignancies recently proposed by the World Health Organization. In the European Organization for Research and Treatment of Cancer classification for cutaneous lymphomas, they would be classified either as CD30- large T-cell lymphoma, small/medium pleomorphic T-cell lymphoma, or subcutaneous T-cell lymphoma. Precise clinicopathologic and prognostic features of all of them have not yet been well characterized. We studied retrospectively 81 biopsies from 50 patients with subcutaneous, blastic natural killer (NK), NK/T-cell, or other non-mycosis fungoides cytotoxic T-cell lymphomas of the skin. Clinical, morphologic, phenotypical, and genetic features and data on Epstein-Barr virus association allowed us to classify our cases according to the following 7 categories: a) subcutaneous "panniculitis-like" T-cell lymphoma (SPTCL): 10 cases (estimated 5-year survival: 80%); b) blastic NK-cell lymphoma: 12 cases (estimated 5-year survival: 0%); c) nasal-type extranodal NK/T-cell lymphoma: 5 patients (estimated 5-year survival: 0%); d) epidermotropic CD8+ T-cell lymphoma: 5 cases (estimated 5-year survival: 0%); e) cutaneous gamma/delta T-cell lymphoma: 8 cases (estimated 5-year survival: 0%); f) cutaneous alpha/beta pleomorphic T-cell lymphoma: 8 cases (estimated 5-year survival: 0%); and g) cutaneous medium/large pleomorphic T-cell lymphoma, not otherwise specified: 2 cases. Our study shows that these cutaneous lymphomas can be classified according to precise diagnostic categories. With the exception of SPTCL, analysis of follow-up data from our patients showed that these groups of lymphomas are characterized by an aggressive course, regardless of the diagnostic category.
CD56+ lymphoma with skin involvement: clinicopathologic features and classification. Gniadecki R, Rossen K, Ralfkier E, Thomsen K, Skovgaard GL, Jonsson V. Departments of Dermatology and Pathology, Bispebjerg Hospital, Copenhagen, Denmark.	Arch Dermatol. 2004 Apr;140(4):427-36. Abstract quote   BACKGROUND: Extranodal lymphomas expressing CD56 (neuronal cell adhesion molecule) are characterized by a high incidence of cutaneous involvement and a very aggressive clinical course. Knowledge about the prognosis and clinicopathologic features of CD56(+) lymphomas with skin involvement is very limited. OBJECTIVES: To determine survival and prognostic factors for extranodal CD56(+) lymphomas with skin involvement and to describe their clinicopathologic features. DESIGN: Retrospective literature survey and case studies. PATIENTS: A total of 181 patients with CD56(+) lymphoma involving the skin: 177 cases from the literature and 4 new cases. MAIN OUTCOME MEASURE: Survival and its dependence on the following putative prognostic factors: staging, histopathologic findings, lymphocyte markers, T-cell receptor gene rearrangement, Epstein-Barr virus infection, treatment modality. RESULTS: Three major subtypes of CD56(+) lymphoma in the skin were distinguished: blastic lymphoma, nasal-type natural killer-cell/T-cell lymphoma, and subcutaneous panniculitislike lymphoma. The disease disseminated readily, mainly to lymph nodes, bone marrow, the central nervous system, and the liver, but 45% of patients had a purely cutaneous disease at presentation. All subtypes had a very aggressive course with a median survival of 14 months. The main risk factors were age older than 55 years (hazard ratio [HR], 2.5; 95% confidence interval [CI], 1.8-3.2), systemic dissemination at presentation (HR, 2.0; 95% CI, 1.5-3.3), and lack of CD30 (HR, 3.8; 95% CI, 1.4-4.9) or CD4 expression (HR, 1.56; 95% CI, 1.06-2.57). The different treatment modalities did not improve survival. CONCLUSIONS: CD56(+) lymphomas involving the skin are rare and extremely aggressive regardless of their histologic presentation and the extent of skin involvement. No effective treatment is available. The risk of death is particularly increased in older patients with CD30(-)CD4(-) lymphomas.
Cytotoxic/natural killer cell cutaneous lymphomas. Report of EORTC Cutaneous Lymphoma Task Force Workshop. Santucci M, Pimpinelli N, Massi D, Kadin ME, Meijer CJ, Muller-Hermelink HK, Paulli M, Wechsler J, Willemze R, Audring H, Bernengo MG, Cerroni L, Chimenti S, Chott A, Diaz-Perez JL, Dippel E, Duncan LM, Feller AC, Geerts ML, Hallermann C, Kempf W, Russell-Jones R, Sander C, Berti E; EORTC Cutaneous Lymphoma Task Force. Department of Human Pathology and Oncology, University of Florence Medical School, Florence, Italy.	Cancer 2003 Feb 1;97(3):610-27 Abstract quote BACKGROUND: Cutaneous lymphomas expressing a cytotoxic or natural killer (NK) cell phenotype represent a group of lymphoproliferative disorders for which there is currently much confusion and little consensus regarding the best nomenclature and classification. METHODS: This study analyzes 48 cases of primary cutaneous lymphoma expressing cytotoxic proteins and/or the NK cell marker, CD56. These cases were collected for a workshop of the European Organization for Research and Treatment of Cancer Cutaneous Lymphoma Task Force, to better clarify the clinical, morphologic, and phenotypic features of these uncommon tumors. RESULTS: Several categories with different clinical and pathologic features were delineated: 1) aggressive, CD8+, epidermotropic, cytotoxic T-cell lymphoma; 2) mycosis fungoides, cytotoxic immunophenotype variant; 3) subcutaneous panniculitis-like T-cell lymphoma; 4) NK/T-cell lymphoma, nasal type; 5) CD4+, NK cell lymphoma; 6) blastoid NK cell lymphoma; (7) intravascular NK-like lymphoma; and 8) cytotoxic, peripheral T-cell lymphoma. CONCLUSIONS: Our data show that primary cutaneous cytotoxic/NK cell lymphomas include distinct groups of diseases, clinically, histologically, and biologically. Because the finding of a cytotoxic phenotype often has prognostic significance, the routine use of cytotoxic markers in the diagnosis and classification of cutaneous lymphomas should be expanded.
Clinicopathological analyses of 5 Japanese patients with CD56+ primary cutaneous lymphomas. Kojima H, Mukai HY, Shinagawa A, Yoshida C, Kamoshita M, Komeno T, Hasegawa Y, Yamashita Y, Mori N, Nagasawa T. Division of Hematology, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki, 305-8575, Japan.	Int J Hematol 2000 Dec;72(4):477-83 Abstract quote We analyzed the clinicopathological features of 5 Japanese patients with CD56+ primary cutaneous lymphomas (3 men and 2 women aged 25 to 73 years). Except for 1 patient in whom bone marrow involvement was simultaneously observed, all patients presented with cutaneous lesions. Based on their Epstein-Barr virus (EBV) status, we categorized these patients into 2 groups, namely EBV-encoded small RNA-1 (EBER-1) (3 patients) and EBER-1- (2 patients). Generalized lymphadenopathy and bone marrow involvement were observed only in EBER-1 patients. Morphologically, angiocentric proliferation was more prominent in EBER-1+ patients and was accompanied by panniculitis-like changes. The lymphomas in EBER-1- patients featured monomorphic proliferation of lymphoblastic cells with no cytoplasmic granules. Phenotypically, CD3-, cytoplasmic CD3 epsilon+, and CD56+ were common findings in both types. The EBER-1- type showed an additional distinguishing feature, CD7+, CD4+, CD8-, HLA-DR+, and terminal deoxynucleotidyl transferase-positive (TdT+) phenotype. The lymphoma was primarily resistant in the EBER-1+ type, and the patients died within 6 months of admission. In contrast, the lymphoma in the EBER-1- patients was originally chemosensitive. Collectively, we consider there to be at least 2 types of CD56+ primary cutaneous lymphomas, corresponding to nasal-type natural killer (NK)/T-cell lymphomas (EBER-1+) and blastic NK-cell lymphomas (EBER-1-).
Blastoid NK cell leukemia/lymphoma with cutaneous involvement. Ginarte M, Abalde MT, Peteiro C, Fraga M, Alonso N, Toribio J. Department of Dermatology, Complejo Hospitalario Universitario, Faculty of Medicine, Santiago de Compostela, Spain.	Dermatology 2000;201(3):268-71 Abstract quote Malignant neoplasms from natural killer (NK) cells are characterized by their positivity for CD56 and absence of monoclonal TCR gene rearrangement. Recently, they have been classified into four main types (nasal and nasal-type NK cell lymphoma, aggressive NK cell leukemia/lymphoma, and blastoid NK cell leukemia/lymphoma), based on clinical features, racial predisposition, presence of azurophilic granules, immunophenotype and association with Epstein-Barr virus (EBV) infection. A 72-year-old Caucasian man presented with a malignant neoplasm comprised of blastoid cells without azurophilic granules in the Giemsa stain, with positivity for CD2, CD4, HLA-DR, CD45 and CD56, and negativity for CD3 (surface and cytoplasmic) and CD5. In situ hybridization for EBV and PCR analysis of rearrangement of the T cell receptor gene were negative. Based on these results, a diagnosis of blastoid NK cell lymphoma was made. In this case the first clinical manifestations were the cutaneous lesions, and, although the disease was already advanced at the diagnosis, the patient responded completely to the treatment and remains asymptomatic 14 months after diagnosis.
Natural killer/natural killer-like T-cell lymphoma, CD56+, presenting in the skin: an increasingly recognized entity with an aggressive course. Mraz-Gernhard S, Natkunam Y, Hoppe RT, LeBoit P, Kohler S, Kim YH. Departments of Dermatology, Pathology, and Radiation Oncology, Stanford University School of Medicine, Stanford, CA 94305, USA.	J Clin Oncol 2001 Apr 15;19(8):2179-88 Abstract quote PURPOSE: To describe and identify the clinical and pathologic features of prognostic significance for natural killer (NK) and NK-like T-cell (NK/T-cell) lymphoma presenting in the skin. PATIENTS AND METHODS: This study was a retrospective review of 30 patients with CD56+ lymphomas initially presenting with cutaneous lesions, with analysis of clinical and histopathologic parameters. RESULTS: The median survival for all patients was 15 months. Those with extracutaneous manifestations at presentation (11 patients) had a shorter median survival of 7.6 months as compared with those without extracutaneous involvement (17 patients), who had a more favorable median survival of 44.9 months (P =.0001). Age, gender, extent of cutaneous involvement, and initial response to therapy had no statistically significant effect on survival. Seven patients (24%) had detectable Epstein-Barr virus (EBV) within neoplastic cells. The patients with tumor cells that coexpress CD30 (seven patients) have not yet reached a median survival after 35 months of follow-up as compared with those with CD30- tumor cells (20 patients), who had a median survival of 9.6 months (P <.02). Routine histopathologic characteristics had no prognostic significance nor did the presence of CD3epsilon, EBV, or multidrug resistance. CONCLUSION: NK/T-cell lymphoma is an aggressive neoplasm; however, a subset with a more favorable outcome is identified in this study. The presence of extracutaneous disease at presentation is the most important clinical variable and portends a poor prognosis. The extent of initial skin involvement does not reliably predict outcome. Patients from the United States with NK/T-cell lymphoma presenting in the skin have a low incidence of demonstrable EBV in their tumor cells. Patients with coexpression of CD30 in CD56 lymphomas tend to have a more favorable outcome.
A Case of Primary Cutaneous CD56+, TdT+, CD4+, Blastic NK-Cell Lymphoma in a 19-year-old Woman. Chang SE, Choi HJ, Huh J, Choi JH, Sung KJ, Moon KC, Koh JK. Department of Dermatology (S.E.C., J.H.C., K.J.S., K.C.M., J.K.K.) and Pathology (H.J.C., J.H.), Asan Medical Center, College of Medicine, University of Ulsan, Seoul, Korea.	Am J Dermatopathol 2002 Feb;24(1):72-5 Abstract quote The classification of blastic or blastoid natural killer (NK)-cell lymphoma is controversial. Reports of primary cutaneous blastic CD56+ NK-cell lymphoma are rare, which necessitates further clinicopathologic definition of this type of lymphoma. Most CD56+ lymphomas display angiocentric histologic features, especially in Asian patients, and these are mostly associated with the presence of Epstein-Barr virus (EBV) genome and with an aggressive clinical course. We report on a young woman with a primary cutaneous blastic NK lymphoma which showed no angiocentric features but showed an unusual immunophenotype; CD56+, TdT+, CD4+, EBV-, and germline configuration of T-cell receptor gene. This unusual lymphoblastic lymphoma seems to have an immature or progenitor NK cell lineage.
Cutaneous natural killer/T-cell lymphoma Michael A. Radonich, MD Rossitza Lazova, MD Jean Bolognia, MD New Haven, Connecticut	J Am Acad Dermatol 2002;46:451-6 Abstract quote Lymphomas are classified as either Hodgkin's or non-Hodgkin's. The 2 subtypes of non-Hodgkin's lymphoma that can present primarily in the skin are cutaneous T-cell lymphoma and cutaneous B-cell lymphoma, both of which tend to be low-grade malignant neoplasms. Recently another distinct subtype of lymphoma was discovered, the natural killer (NK)/T-cell lymphoma, which can involve the skin in a primary or secondary fashion. The NK/T-cell subtype of lymphoma is characterized by the expression of the NK-cell antigen CD56. These CD56+ lymphomas are further subdivided into nasal NK/T-cell lymphomas that commonly present as midfacial destructive disease and non-nasal NK/T-cell lymphomas that often arise in extranodal locations, including the skin. We report a case of aggressive NK-cell leukemia/lymphoma with numerous secondary cutaneous lesions and review the clinical and histopathologic spectrum of non-nasal CD56+ lymphomas, with an emphasis on the dermatologic findings.
SYSTEMIC
Hypersensitivity to mosquito bites as the primary clinical manifestation of a juvenile type of Epstein-Barr virus-associated natural killer cell leukemia/lymphoma Yoshiki Tokura, MD Shigehiko Ishihara, MD Shinichi Tagawa, MD Naohiro Seo, PhD Kouichi Ohshima, MD Masahiro Takigawa, MD Hamamatsu, Kashiwara, Osaka, and Fukuoka, Japan	J Am Acad Dermatol 2001;45:569-78 Abstract quote Hypersensitivity to mosquito bites or mosquito allergy is a mysterious disorder that has been reported mainly in Japanese patients (at least 58 patients) in the first two decades of life. The skin lesion at bite sites is typically a bulla that develops into necrosis. Patients simultaneously exhibit a high temperature and general malaise and subsequently may experience lymphadenopathy and hepatosplenomegaly. Recent studies have revealed that this mosquito hypersensitivity is associated with chronic Epstein-Barr virus infection and natural killer cell leukemia/lymphoma. The natural killer cell, infected with monoclonal (or oligoclonal) Epstein-Barr virus, seems to be involved in the pathogenesis of the hypersensitivity. Half of the patients reported died of hemophagocytic syndrome (or malignant histiocytosis), granular lymphocyte proliferative disorder, or lymphomas. We propose that this disease, defined as the triad of hypersensitivity to mosquito bites, chronic Epstein-Barr virus infection, and natural killer cell leukemia/lymphoma, is a clinical entity mostly seen in Asians.
Aggressive Epstein-Barr Virus-Associated, CD8+, CD30+, CD56+, Surface CD3–, Natural Killer (NK)-Like Cytotoxic T-Cell Lymphoma Jianguo Tao, M.D. , Ph.D. ; Suresh G. Shelat, M.D. , Ph.D. ; Elaine S. Jaffe, M.D. ; Adam Bagg, M.D. From the Department of Pathology and Laboratory Medicine (J.T., S.G.S., A.B.), University of Pennsylvania, Philadelphia, Pennsylvania; and the Laboratory of Pathology (E.S.J.), NIH-NCI, Bethesda, Maryland, U.S.A.	Am J Surg Pathol 2002;26:111-118 Abstract quote We report an unusual case of aggressive natural killer (NK)-like cytotoxic T-cell lymphoma in a previously healthy immunocompetent West African male. He presented with a fever of unknown origin, subsequently developed erythematous skin nodules, generalized lymphadenopathy, and hepatosplenomegaly, and then died of multiple organ failure. A skin nodule and lymph node biopsy showed an infiltrate of pleomorphic atypical medium and large lymphoid cells with extensive necrosis and prominent apoptosis. Peripheral blood and ascites also harbored these cells, with cytology revealing irregular nuclear folding and basophilic cytoplasm, and some with azurophilic cytoplasmic granules. Flow cytometry and immunohistochemistry demonstrated the expression of CD2, CD7, CD8, CD30, CD56, and cytoplasmic but not surface CD3. In situ hybridization demonstrated Epstein-Barr virus transcripts. A monoclonal T-cell receptor chain gene rearrangement was detected by polymerase chain reaction. This is the first reported case of an NK-like T-cell lymphoma with these unusual features, making precise classification difficult. Some features suggest an NK1.1 or NKT lymphocyte origin. Because the earliest clinical manifestation was splenomegaly and abnormal liver function, the normal cellular counterpart may be a distinct subset of NK1.1 cells normally present in hepatosplenic sinusoids. This tumor disseminated early and pursued a fulminant clinical course, thus emphasizing the importance of early recognition and diagnosis.

 

HISTOLOGICAL TYPES	CHARACTERIZATION
GENERAL	Broad cytologic spectrum Nuclei often irregular with granular chromatin Moderate amount of pale to clear cytoplasm Azurophilic granules in Giemsa touch preparations Many admixed inflammatory cells Angiocentric and angiodestructive growth common Fibrinoid necrosis of blood vessels Extensive coagulative necrosis and apoptosis common Epithelium may be infiltrated by lymphoma cells
	Am J Surg Pathol 1996;20:103-11. Pathol Pattern 1999;111(Suppl 1):S46-S55. Am J Surg Pathol 1997;21:242-8. Am J Surg Pathol 1997;21:1223-30. Am J Surg Pathol 1998;22:135-7. Three major groups of natural killer (NK) cell-associated hematolymphoid malignancy: Nasal and nasal-type NK-cell lymphoma Aggressive NK-cell lymphoma/leukemia Blastic NK-cell lymphoma/leukemia
	Am J Surg Pathol 1995;19:284-96. Arch Dermatol 1996;132:550-3 Am J Surg Pathol 1999;23:137-46. Another group of patients with unique immunohistochemical characteristics has been reported: Express both the T helper/inducer cell marker CD4 and the NK-cell marker CD56 Suggest a T-cell origin, but the negativity of the CD3 (surface and cytoplasmic) and the other T-cell-related antigen, CD2, and the absence of clonal rearrangement of the T-cell receptor (TCR) gene are against this hypothesis
ANAPLASTIC
Pediatric CD56+ anaplastic large cell lymphoma: a review of the literature. Dunphy CH, DeMello DE, Gale GB. Department of Pathology and Laboratory Medicine, CB# 7525, UNC, Chapel Hill, NC 27599-7525, USA.	Arch Pathol Lab Med. 2006 Dec;130(12):1859-64. Abstract quote CONTEXT: Anaplastic large cell lymphomas (ALCLs) are a heterogeneous group of CD30+ large cell lymphomas that, according to the World Health Organization classification, are defined as being of T-cell origin, based on immunophenotype, and/or the finding of a T-cell gene rearrangement by molecular studies. Most cases express cytotoxic granule-associated proteins. Relatively recent data have suggested that some T-cell ALCLs are derived from cytolytic CD4+ cells, gammadelta T cells, or natural killer-like (CD56+ or CD57+) T cells. We encountered a pediatric case of CD56+, anaplastic lymphoma kinase-positive ALCL of apparent natural killer-like T-cell origin (showing positivity for CD2, cytoplasmic CD3, surface CD3 partial positivity, CD7, CD8, CD56, TIA-1, and granzyme B). The patient had initial lymph node and multiple sites of cutaneous involvement and an aggressive clinical course with multiple recurrences after varying periods of complete remission. OBJECTIVE: To review the current pediatric literature regarding the incidence, differential diagnosis, and clinical course of such cases. DATA SOURCES: Relevant articles indexed in PubMed (National Library of Medicine) between 1975 and 2006. CONCLUSIONS: Our review did not confirm a uniformly aggressive clinical course in pediatric cases of CD56+ ALCLs. Such cases suggest the usefulness of the analysis of CD56-positivity in additional cases of ALCL in an attempt to accrue additional information on this condition. Future accrual of such cases may address whether such cases should be treated more aggressively or with possible targeted therapeutic regimens.
BLASTIC/BLASTOID (CD4+/CD56+)
CD4+ CD56+ Hematodermic Neoplasm. Cibull TL, Thomas AB, O'malley DP, Billings SD. From the *Departments of Pathology and Laboratory Medicine; and daggerDepartment of Dermatology, Indiana University, Indianapolis, IN.	Am J Dermatopathol. 2007 Feb;29(1):59-61. Abstract quote We report a case of a 75-year-old man with a cutaneous CD4+CD56+ hematodermic neoplasm. CD4+CD56+ hematodermic neoplasms are rare and commonly present as cutaneous lesions. This is an important diagnosis in the differential diagnosis of cutaneous hematologic malignancies because of the extremely poor prognosis.
CD4(+) CD56(+) Lineage-Negative Malignancies Are Rare Tumors of Plasmacytoid Dendritic Cells. Reichard KK, Burks EJ, Foucar MK, Wilson CS, Viswanatha DS, Hozier JC, Larson RS. From the Department of Pathology, University of New Mexico, Albuquerque, NM.	Am J Surg Pathol. 2005 Oct;29(10):1274-83. Abstract quote   CD4(+) CD56(+) lineage-negative malignancies are difficult to diagnose and classify. Recent studies have suggested that these malignancies may derive from plasmacytoid dendritic cells (pDC). In this report, we examine 10 cases of CD4+, CD56+ lineage-negative malignancies that presented in various tissue sites. The goal was to identify the morphologic, immunophenotypic, and genotypic findings to devise a diagnostic approach to tissue biopsies of these lesions and to confirm the proposed cell of origin. The mean age was 66 years (range, 45-80 years) with a male predominance (8 males/2 females). Frequent sites of disease included skin (60%) and peripheral blood/bone marrow (70%). Tumor cells were positive for CD45, CD43, CD4, and CD56 (9 of 10). The pDC markers, CD123 (9 of 10) and CD45RA (10 of 10), were detected by immunoperoxidase staining. Also noted was CD2 positivity (1 case), weak CD7 positivity (4 of 8 cases), weak CD33 (4 of 9 cases), TdT (2 cases), and CD68 (2 cases). All cases were otherwise negative for EBV (EBER), B-cell, T-cell, myeloid, and NK cell markers. T-cell receptor-gamma gene rearrangement was negative in all cases. Complex structural chromosomal abnormalities were seen in 3 of 5 cases, a subset of which may be recurrent in pDC malignancy. Overall prognosis was poor despite multiagent chemotherapy and/or radiation.   Our study confirms that CD4+/CD56+ lineage-negative tumors are derived from pDC and have characteristic clinical, histopathologic, and immunophenotypic features. Furthermore, these rare neoplasms can be readily diagnosed using recently developed immunoperoxidase techniques.
Blastic NK-Cell Lymphomas (Agranular CD4+CD56+ Hematodermic Neoplasms) A Review Tony Petrella, MD, etal.	Am J Clin Pathol 2005;123:662-675 Abstract quote Blastic natural killer (NK) cell lymphoma (also termed CD4+CD56+ hematodermic neoplasm) is a recently described entity, with the first case reported in 1994. It was suggested initially that the disease originates from NK cells. Since 1994, single cases and a few small series have been published. In this review, data from the literature and a series of 30 cases from the French and Dutch study groups on cutaneous lymphomas are discussed. The major clinical, histopathologic, and phenotypic aspects of the disease and diagnostic criteria and data suggesting a plasmacytoid dendritic cell origin for the tumor cells are provided.
Non-B, non-T neoplasms with lymphoblast morphology: further clarification and classification. Karube K, Ohshima K, Tsuchiya T, Yamaguchi T, Suefuji H, Suzumiya J, Harada M, Kikuchi M.	Am J Surg Pathol. 2003 Oct;27(10):1366-74 Abstract quote.   SUMMARY: We studied the morphologic, immunohistochemical, and clinical characteristics of 158 cases of lymphoblastic lymphoma. Based on immunophenotyping and cell lineage, cases were classified into B-cell type (CD20,CD19 or CD79a+, n = 53), T-cell type (surface CD3+, n = 84), and non-B, non-T type (B cell marker- and surface CD3-, n = 21). The latter group was further divided based on immunohistochemistry into: 1) CD7+ stem cell lymphoma (CD7+SCL) [CD4-, CD7+, CD33+/-, CD56-], 2) blastic natural killer cell lymphoma (B-NKL) [CD4-, CD7+/-, CD33-, CD56+, CD123-], 3) myeloid/NK precursor cell leukemia (M/NKL) [CD4-, CD7+, CD33+, CD56+], and 4) CD4+CD56+ hematodermic malignancy (CD4+CD56+) type [CD4+, CD7+/-, CD33-, CD56+, CD123+]. The CD7+SCL and M/NKL types frequently exhibited bone marrow invasion and mediastinal masses. All CD4+CD56+ types were associated with skin lesions. B-NKL type is included into Blastic NK lymphoma in new World Health Organization classification with CD4+CD56+ type. But the cases of B-NKL were more reminiscent of CD7+SCL or M/NKL type than the CD4+CD56+ type, both clinically and histologically. We propose that blastic NK lymphoma, a disease entity in the new WHO classification, should be divided into two types based on phenotypes and clinical features. The non-B, non-T lymphomas exhibited poorer prognoses, similar to that of B-cell lymphomas, than T-cell type tumors (P = 0.009). Among the 21 tumors, the prognosis of the four subtypes did not differ significantly; however, cases receiving aggressive chemotherapy and stem cell transplantation had a more favorable prognosis than those receiving only traditional chemotherapy and radiation therapy (P = 0.0089).
Blastic natural killer cell leukemia/lymphoma: a clinicopathologic study. DiGiuseppe JA, Louie DC, Williams JE, Miller DT, Griffin CA, Mann RB, Borowitz MJ. Department of Pathology, The Johns Hopkins Medical Institutions, Baltimore, Maryland 21287-6417, USA.	Am J Surg Pathol 1997 Oct;21(10):1223-30 Abstract quote The classification of natural killer (NK)-cell and NK-like T-cell malignancies has undergone significant evolution in recent years. Although examples of NK-cell tumors resembling acute leukemia have been described anecdotally as blastic, blastoid, or monomorphic NK-cell leukemia/lymphoma (NKL/L), the clinical and pathologic features of these tumors have not been systematically defined. We report four patients with blastic NKL/L and describe the clinical, pathologic, and immunophenotypic findings in these cases. All patients were elderly (58-82 years) and presented with cutaneous plaques. Two patients also had adenopathy, and three patients had marrow involvement at presentation. Biopsy of cutaneous lesions showed atypical superficial and deep dermal lymphoid infiltrates. Involved lymph nodes were architecturally effaced by an interfollicular infiltrate with blastic cytologic features. In Wright-Giemsa-stained blood or marrow smears, tumor cells had finely distributed nuclear chromatin, many with nucleoli, and variable amounts of cytoplasm. In contrast to many NK and NK-like T-cell disorders, azurophilic cytoplasmic granules were absent or inconspicuous. The tumor cells were immunophenotypically distinctive. They expressed intermediate density CD45, as is characteristic of blasts; in addition, the cells were positive for HLA-DR, CD2, CD4, and the NK-associated antigen CD56. Surface CD3, cytoplasmic CD3, and CD5 were negative in all cases tested, whereas CD7 was expressed in two cases. In formalin-fixed tissue, tumor cells marked with antibodies to CD43, but not with other T- or B-lineage-related antibodies. All three cases studied for Epstein-Barr viral RNA by in situ hybridization were negative. Although treatments varied, all three patients with clinical follow-up died within months of the diagnosis. The clinical course in two patients culminated in an overtly leukemic phase. These findings suggest that blastic NKL/L represents a distinct clinicopathologic entity, characterized by cutaneous, nodal, and marrow involvement by blastic cells with immunophenotypic characteristics of true NK cells. The disease afflicts elderly patients, pursues an aggressive course, and may culminate in overt leukemia.
CD56+/CD4+ Lymphomas and Leukemias Are Morphologically, Immunophenotypically, Cytogenetically, and Clinically Diverse Christiane K. Rakozy, MD,1 Anwar N. Mohamed, MD,1 Trieu D. Vo, PhD,2 Ghada Khatib, MD,1 P. Michael Long, PhD,1 David Eilender, MD,3 and Margarita Palutke, MD	Am J Clin Pathol 2001;116:168-176 Abstract quote CD56, a neural adhesion molecule, is a marker of natural killer (NK) lymphocytes as well as a subgroup of CD8+ T cells. Normal lymphocytes with a CD56/CD4 phenotype are scarce. Physiologic increases may occur in patients with immunosuppression, chronic inflammation, and autoimmune disorders. We report 4 cases of lymphomas/leukemias with the unusual CD56/CD4 phenotype. Two were of T-cell and 2 of true NK-cell origin. The T-cell lymphomas had large granular lymphocyte morphologic features and splenomegaly. One patients had a benign course; the other died within months of the leukemia diagnosis. The 2 NK cell lymphomas had blastic morphologic features, initially involved skin, and had a very aggressive clinical course; 1 patient died of acute leukemia, and 1 had recurrence after bone marrow transplantation. Cytogenetic analyses did not show a consistent pattern of abnormalities. The NK lymphoma with acute leukemia had a t(2;5) but was CD30– and anaplastic lymphoma kinase negative. Although CD56+/CD4+ lymphomas/leukemias are a heterogeneous group, there may be a distinct subgroup of NK lymphoblastoid lymphomas of the skin, judging from our cases, as well as those previously reported.
Agranular CD4+CD56+ blastic natural killer leukemia/lymphoma. Kimura S, Kakazu N, Kuroda J, Akaogi T, Hayashi H, Nishida K, Abe T. Division of Hematology, Kyoto Second Red Cross Hospital, Japan.	Ann Hematol 2001 Apr;80(4):228-31 Abstract quote Blastic natural killer cell leukemia/lymphoma (blastic NKL/L) is characterized by blastic morphology and a distinctive immunophenotype combining blastic features and cytologically resembling acute myeloid or lymphoid leukemia. The clinical, pathologic, and cytogenetic features of blastic NKL/L have not yet been systematically identified. We report herein a case of blastic NKL/L with skin lesion, adenopathy, and systemic lymphoadenopathy. The identified tumor cells were positive for CD4 and CD56, and negative for T-cell, B-cell, and myeloid markers. T-cell receptor beta, gamma, delta, and immunoglobulin heavy chain genes in the bone marrow cells showed germ-line configurations. Southern blot analysis with a terminal probe did not reveal any Epstein-Barr virus infection. Although patients diagnosed as blastic NKL/L have generally shown chemotherapy resistance and poor prognosis, our patient was treated with a combined chemotherapy, which is also used for acute lymphoblastic leukemia, and has maintained complete remission (CR) for more than 13 months. In addition to clinical investigations, we thoroughly analyzed his karyotype by using a combination of G-banding and a new technique, spectral karyotyping. The karyotype was described as 45, XY, der(1)t(1;20)(p32;q11.2), der(6) (1pter-->1p32:: 6p21.1-->6q13:: 7q11.2-->7qter), der(7) t(7;20)(q11.2;q11.2), t(13;14)(q14;q32), der(13)t(6;13) (p21.1; q14), -20.
Blastic Natural Killer Cell Lymphoma/Leukemia A Report of Seven Cases Michael G. Bayerl, MD Christiane K. Rakozy, MD Anwar N. Mohamed, MD Trieu D. Vo, PhD Michael Long, PhD David Eilender, MD and Margarita Palutke, MD	Am J Clin Pathol 2002;117:41-50 Abstract quote Only a few blastic natural killer (NK) cell leukemias and lymphomas have been reported. As such, the clinicopathologic spectrum of this disease is incompletely understood. We report 7 cases of blastic NK cell lymphoma/leukemia. All patients were men, 5 white and 2 Arab American. All cases exhibited blastic morphologic features and were CD3– and CD56+ with germline T-cell receptor genes. Five cases were CD4+ and involved the skin. Both CD4– cases never involved the skin. Other markers of mature NK cells such as CD16, CD57, and TIA-1 were expressed infrequently. Three cases were CD33+. One CD33+ case had a clonal rearrangement of the immunoglobulin heavy chain gene. Skin and lymph nodes were involved most often, with frequent evolution to a leukemic phase. Initial responses to therapy were achieved in most patients, but the tumors invariably recurred.
B-CELL ANTIGENS
T-cell/natural killer cell lymphoblastic lymphoma with an unusual coexpression of B-cell antigens. Gloeckner-Hofmann K, Ottesen K, Schmidt S, Nizze H, Feller AC, Merz H. Institute of Pathology, Medical University of Luebeck, Germany.	Ann Hematol 2000 Nov;79(11):635-9 Abstract quote Lymphoblastic lymphomas are usually B- or T-cell neoplasms. There exists a small group of T-cell lymphomas additionally coexpressing cytotoxic or natural killer (NK)-cell markers, supporting the hypothesis of a common T/NK-cell precursor and respective neoplasms. Clinically, lymphatic neoplasms of T/NK-cell phenotype are either extranodal lymphomas or acute leukemias. The clinical course of these T/NK neoplasms cannot be predicted by morphology and/or phenotype alone. However, the expression of a heterogeneous (T + NK or myeloid) marker profile or of "early" antigens (such as TdT, CD10, RAG1, RAG2) render them more likely to be in the acute leukemia group. We present a case of a 63-year-old woman with a bone marrow infiltrate, enlarged lymph nodes, and B-symptoms. A cervical lymph node biopsy showed a monomorphic blastic infiltrate with a T-cell phenotype, coexpressing NK markers (CD56, CD57, NK1) and B-cell antigens (CD20, CD79). To the best of our knowledge, this is a newly recognized phenotype that has not been reported before. T/NK-cell lymphomas, including blastic NK-cell leukemia/lymphoma and T-lymphoblastic lymphomas, have to be included in the differential diagnosis. Both groups have a different clinical behavior and prognosis. In particular, T/NK-cell lymphomas associated with an Epstein Barr virus infection are clinically very aggressive neoplasms.
	J Am Acad Dermatol 2001;44:231-8 Japanese patient with a unique hematolymphoid malignancy characterized by an involvement of skin, nasopharyngeal region, bone marrow, lymph node, and a CD4+ CD43+ CD56+ CD2–CD3–CD8– and terminal deoxynucleotidyl transferase phenotype Clinically, the cutaneous eruptions were purplish, hard, multiple nodules Histologically, a massive proliferation of atypical pleomorphic cells with medium-sized nuclei were observed throughout the dermis No clonal rearrangement of T-cell receptor (TCR)- gene or immunoglobulin heavy chain J gene was found, and no positive identification of EBV by in situ hybridization for EBV-encoded small nuclear RNA was found Patient underwent high-dose chemotherapy with autografting of peripheral blood stem cells; however, the tumors quickly relapsed Additional data from 17 cases of lymphoid malignancy from the literature sharing immunophenotypic and genotypic features similar to those of this case, including CD2–CD4+CD56+ and germline rearrangement of TCR Although the cellular origin could not be decided, this malignancy was found to have 100% affinity for skin, a short course, and poor prognosis
NORMAL HISTOLOGY
Nasal natural killer cell/t-cell lymphoma showing cellular morphology mimicking normal lymphocytes. Chinen K, Kaneko Y, Izumo T, Ohkura Y, Matsubara O, Tsuchiya E. Departments of Pathology (Drs Chinen, Izumo, Ohkura, and Tsuchiya) and Cancer Chemotherapy (Dr Kaneko), Saitama Cancer Center, Ina-machi, Japan; and the Department of Pathology, National Defense Medical College, Tokorozawa City, Japan (Dr Matsubara).	Arch Pathol Lab Med 2002 May;126(5):602-5 Abstract quote We report the autopsy case of a 34-year-old Japanese man with a nasal natural killer (NK)-cell/T-cell lymphoma. The patient developed the disease at 32 years of age, and a biopsy of the nasopharynx revealed pleomorphic lymphoma cell proliferation. Radiotherapy was performed, but the patient eventually died of respiratory failure. After radiotherapy, no histologic evidence of malignancy was obtained with biopsy materials featuring lymphocytic infiltration. Autopsy studies, including in situ hybridization for Epstein-Barr virus-encoded RNA, revealed generalized infiltration of normal lymphocyte-like, UCHL-1-positive, and Epstein-Barr virus-encoded RNA-positive lymphoma cells. Monoclonal proliferation of the Epstein-Barr virus-carrying cells was verified by means of Southern blot analysis. Retrospectively, we concluded that the normal lymphocyte-like presentation of the lymphoma cells, probably influenced by radiotherapy, prevented pathologists from recognizing the lymphoma. The utility of in situ hybridization for Epstein-Barr virus-encoded RNA in identification of tumor cells is emphasized with respect to the present case.

 

SPECIAL STAINS/ IMMUNOPEROXIDASE	CHARACTERIZATION
Special stains
IMMUNO- HISTOCHEMICAL MARKER	RESULT
CD56	+
CD45RO, CD43	+
CD3, cytoplasmic	+
CD2	+
Cytotoxic molecules (perforin, granzymeB, TIA-1)	+
Epstein-Barr virus	+ >90% of nasal type cases but figure may be lower in Caucasians
Ki-67	High proliferative rate, usually >80%
TCR genes	Germline
Immunoreactivity of B-cell markers (CD79a, L26) in rare cases of extranodal cytotoxic peripheral T- (NK/T-) cell lymphomas. Blakolmer K, Vesely M, Kummer JA, Jurecka W, Mannhalter C, Chott A. Department of Clinical Pathology, General Hospital Vienna, University of Vienna, Austria.	Mod Pathol 2000 Jul;13(7):766-72 Abstract quote The monoclonal antibodies L26 (CD20) and CD79a are very useful reagents for the immunohistochemical assessment of B-cell lineage in lymphoproliferative disorders. Although very few CD20-positive peripheral T-cell lymphomas (PTL) have been reported, comprehensive analyses of CD79a reactivity in extranodal PTL and NK/T-cell lymphomas have not been performed previously. This study investigated CD79a (clone JCB117) and CD20 reactivity in 94 extranodal non-B-cell lymphomas (enteropathy-type intestinal T-cell lymphoma [n = 52], nasal NK/T-cell lymphoma [n = 11], and primary cutaneous PTL [n = 31]) and in 17 cases of nodal PTL, unspecified. In four cases (enteropathy-type intestinal T-cell lymphoma [n = 3] and nasal NK/T-cell lymphoma [n = 1]), the majority of tumor cells stained for CD79a (all CD20 negative) and one cutaneous PTL, unspecified, was CD20 positive (CD79a negative). Extensive immunophenotyping and polymerase chain reaction-based molecular analyses revealed that all five B-cell marker-positive extranodal lymphomas had a cytotoxic phenotype and did indeed represent monoclonal peripheral T-cell proliferations. To minimize the risk of misinterpretation of lymphoma cell lineage, especially in cases of extranodal, lymphoproliferative disease, we suggest the use of both CD79a and CD20 in combination with a panel of antibodies reactive to T cells, such as betaF1 and CD5, and to T cells and NK cells, such as CD3, CD2, CD56, and TIA-1.
CHEMOKINE RECEPTORS
Chemokine Receptor Expression in Cutaneous T cell and NK/T-cell Lymphomas: Immunohistochemical Staining and In Vitro Chemotactic Assay. Yagi H, Seo N, Ohshima A, Itoh T, Itoh N, Horibe T, Yoshinari Y, Takigawa M, Hashizume H. Department of Dermatology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Japan.	Am J Surg Pathol. 2006 Sep;30(9):1111-9 Abstract quote Interactions between chemokines and chemokine receptors are involved in migration and invasion of lymphoma cells. We investigated expression profiles of CXCR3 and CCR4 by immunohistochemistry and flow cytometry, and their biologic behaviors by real-time horizontal chemotaxis assay in cutaneous T cell and NK/T-cell lymphomas (TCLs). Tumor cells in mycosis fungoides (MF) constantly expressed CXCR3 at the patch stage, and expressed CCR4 at the tumor stage and in the folliculotropic variant of MF. Neoplastic cells at the plaque stage expressed CXCR3 and/or CCR4. Sezary cells in the dermis and circulation were positive for CCR4. Epidermotropic atypical cells in pagetoid reticulosis expressed CXCR3. CD30 cells exclusively expressed CCR4 in anaplastic large-cell lymphoma, and CXCR3 and/or CCR4 in lymphomatoid papulosis. In CD8TCL and extranodal NK/TCL characterized by extensive epidermotropism, tumor cells were positive for CXCR3. These data demonstrated preferential expression of CXCR3 in epidermotropic tumor cells, and of CCR4 in dermis-based lymphomas. In chemotaxis assays, CCR4 tumor cells in MF and CXCR3 tumor cells in CD8TCL migrated to thymus and activation-regulated chemokine and inducible protein-10, respectively. Therefore, spatial and temporal interactions between chemokine receptors and their ligands seem to dictate recruitment and retention of lymphoma cells in the skin.
Electron microscopy (EM)
Comparative ultrastructural study of cytotoxic granules in nasal natural killer cell lymphoma, intestinal T-cell lymphoma, and anaplastic large cell lymphoma. Sadahira Y, Akisada K, Sugihara T, Hata S, Uehira K, Muraki N, Manabe T. Department of Pathology, Kawasaki Medical School, 577 Matsushima, Kurashiki 701-0192, Japan.	Virchows Arch 2001 Mar;438(3):280-8 Abstract quote Comparative immunohistochemical and ultrastructural studies were performed on five nasal natural killer (NK) cell lymphoma cases, two intestinal T-cell lymphoma cases, and eight anaplastic large cell lymphoma (ALCL) cases to clarify morphological differences in cytotoxic granules among these cytotoxic lymphomas. Nasal NK-cell lymphomas and intestinal T-cell lymphomas had fine azurophilic granules and displayed dot-like immunostaining of granzyme B- and T-cell intracellular antigen 1 (TIA-1), predominantly in the central area of the cytoplasm. Ultrastructurally, these NK-cell lymphomas and intestinal T-cell lymphomas had two types of cytotoxic granules, type-I granules (dense core granules) and type-II granules (multivesicular bodies), which have been demonstrated in normal large granular lymphocytes in peripheral blood. However, ALCLs did not have azurophilic granules, and only type-II cytotoxic granules were found ultrastructurally, even though they showed similar dot-like immunostained patterns of granzyme B and TIA-1, as seen in NK-cell lymphomas and intestinal T-cell lymphomas. Immunoelectron microscopy revealed that TIA-1 was primarily located at the periphery of the cytoplasmic granules in the NK-cell lymphoma and ALCL cases. These findings suggest that malignant lymphomas with a cytotoxic phenotype can be divided into two types, (azurophilic granule)+, (type-I granule)+, (type-II granule)+ lymphomas and (azurophilic granule)-, (type-I granule)-, (type-II granule)+ lymphomas.

 

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
CD30+ ANAPLASTIC LYMPHOMA
Solitary primary cutaneous CD30+ large cell lymphoma of natural killer cell phenotype bearing the t(2;5)(p23;q35) translocation and presenting in a child. Gould JW, Eppes RB, Gilliam AC, Goldstein JA, Mikkola DL, Zaim MT, Wood GS. Department of Dermatology, Case Western Reserve University, and the Veterans Administration Medical Center, Cleveland, Ohio 44106, USA.	Am J Dermatopathol 2000 Oct;22(5):422-8 Abstract quote Primary cutaneous CD30+ large cell lymphoma is an unusual tumor most commonly seen in adults. Most of these lymphomas are of T-cell origin and carry a good prognosis. We present the case of a 4-year-old girl with stage IEA CD30+ large cell lymphoma with a CD56+ natural killer cell phenotype and the t(2;5)(p23;q35) translocation. After excision, the patient has been free of disease for 44 months. Primary cutaneous CD30+ large cell lymphoma is uncommon in children. To our knowledge, primary cutaneous CD30+ natural killer type lymphoma has not been reported previously. The indolent behavior of this tumor indicates its similarity to other primary cutaneous CD30+ large cell lymphomas and its difference from other CD56+ lymphomas involving the skin, which often exhibit an aggressive clinical course. Cases such as this one illustrate why the use of a single, or even a few, immunohistochemical stains can be misleading in regard to lymphoma classification and prognostication.
LYMPHOMATOID PAPULOSIS
Lymphomatoid papulosis with a natural killer-cell phenoty