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Background

This is a rare soft tissue sarcoma usually located in the deep soft tissue in the groin or lower extremities. It is important to differentiate this tumor from other soft tissue tumors. Recently it has been hypothesized that this tumor probably forms a histologic spectrum with another rare tumor known as Hyalinizing Spindle Cell Tumor with Giant Rosettes.

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 CHARACTERIZATION
INCIDENCE Rare
AGE RANGE-MEDIAN 6-65 years
Mean 35 years
SEX (M:F)
75% males

 

PATHOGENESIS CHARACTERIZATION
CHROMOSOMAL ALTERATIONS-FUS-CREB3L2 or FUS-CREB3L1  

Am J Dermatopathol. 2011 Apr;33(2):140-3.
FUS (16p11) Gene Rearrangement as Detected by Fluorescence In-Situ Hybridization in Cutaneous Low-Grade Fibromyxoid Sarcoma: A Potential Diagnostic Tool.


Patel RM, Downs-Kelly E, Dandekar MN, Fanburg-Smith JC, Billings SD, Tubbs RR, Goldblum JR.
Source


From the *Departments of Pathology; and †Dermatology, University of Michigan, Ann Arbor, MI; ‡Departments of Anatomic Pathology; and §Molecular Pathology, Cleveland Clinic, Cleveland, OH; and ¶Department of Orthopaedic and Soft Tissue Pathology, Armed Forces Institute of Pathology, Washington, DC.
Abstract

Am J Dermatopathol. 2011 Apr;33(2):140-3. Abstract quote

Low-grade fibromyxoid sarcoma (LGFMS) is a rare, typically deep-seated soft tissue neoplasm with deceptively bland cytology and metastatic potential. A t(7;16)(q34;p11) translocation, yielding a FUS/CREB3L2 fusion gene, has been identified in approximately 80%-90% of deep soft tissue LGFMS. Cutaneous fibromyxoid neoplasms occur not infrequently; dermatopathologists rarely consider LGFMS in the differential diagnosis, as this lesion is uncommon in the skin.

We identified a group of superficial LGFMS and a spectrum of other cutaneous fibromyxoid neoplasms and performed fluorescence in situ hybridization (FISH) to assess the frequency of FUS rearrangement. FISH for the chromosomal rearrangement of FUS (16p11), using a dual-color, break-apart probe (Abbott Molecular/Vysis, Des Plaines, IL), was performed on formalin-fixed paraffin-embedded tissue sections from superficial LGFMS (n = 6), myxomas (n = 10), and myxofibrosarcoma/myxoid malignant fibrous histiocytomas (myxoid MFH) (n = 5). One hundred nonoverlapping tumor nuclei per case were evaluated for either fused (normal) or split (translocated) signals. Of the LGFMS, 4 of 6 (67%) showed a rearrangement of FUS (range: 72%-80% positive nuclei per 100 nuclei). The other neoplasms within the differential diagnosis were devoid of any rearrangement involving FUS (range: 0%-2% positive nuclei per 100 nuclei). Our observed frequency of FUS rearrangement in superficial LGFMS is consistent with those published in the literature for more deeply seated lesions.

When applied to suspicious superficial myxoid or fibromyxoid neoplasms, the FUS FISH probe in formalin-fixed paraffin-embedded tissue can be a useful ancillary technique for diagnosis of this uncommon and deceptively bland tumor.
Translocation-positive Low-grade Fibromyxoid Sarcoma: Clinicopathologic and Molecular Analysis of a Series Expanding the Morphologic Spectrum and Suggesting Potential Relationship to Sclerosing Epithelioid Fibrosarcoma: A Study From the French Sarcoma Group.

*University Institute of Pathology, Lausanne, Switzerland
†Léon-Bérard Cancer Center, Lyon ‡Georges-François Leclerc Cancer Center, Dijon §Gustave Roussy Institute, Villejuif ∥Alexis Vautrin Cancer Center, Nancy ¶Claudius Regaud Cancer Center, Toulouse **Genetic Laboratory of Solid Tumors, CNRS UMR 6543 and Nice University Hospital, Nice ††Bergonié Institute and University “Victor Segalen”, Bordeaux, France ♯Jules Bordet Institute, Brussels, Belgium.

 

Am J Surg Pathol. 2007 Sep;31(9):1387-1402. Abstract quote

Low-grade fibromyxoid sarcomas (LGFMS) bear either the t(7,16) (q32-34;p11) or t(11,16) (p11;p11) translocations, resulting in FUS-CREB3L2 or FUS-CREB3L1 fusions, respectively. Heretofore, fusion transcripts were mainly detected in frozen tissues, using reverse transcription-polymerase chain reaction.

In this study, we aimed to develop a reliable method to detect these in paraffin-embedded tissues, and to examine the clinicopathologic characteristics of a series of translocation-positive LGFMS. Sixty-three neoplasms with typical morphologic features of LGFMS and 66 non-LGFMS tumors selected for their resemblance to LGFMS (LGFMS-like tumors) were examined. RNA of sufficient quality could be extracted from 111/129 (86%) cases (59 LGFMS, 52 non-LGFMS). Of all, 48/59 (sensitivity, 81%) LGFMS contained detectable transcripts (45 FUS-CREB3L2, 3 FUS-CREB3L1).

Most relevant clinicopathologic features of fusion-positive LGFMS included predominance in lower extremities (22/48; thigh: 13/48), deep situation (46/48), and occasional presence of unusual histologic features, for example, hypercellular areas (16/48), foci of epithelioid cells (13/48), and giant rosettes (6/48). Most tumors expressed EMA (41/45), at least focally, CD99 (38/41) and bcl-2 (36/41) while being essentially negative for CD34 (2/45), mdm2 (1/41), smooth muscle actin (1/45), S100 protein (0/46), desmin (0/44), h-caldesmon (0/42), keratins (0/44), and CD117 (0/40). Eleven presumed LGFMS were fusion negative. Of all, 7/52 non-LGMFS neoplasms contained FUS-CREB3L2 transcripts, of which 4 had been diagnosed as sclerosing epithelioid fibrosarcoma. In conclusion, FUS-CREB3L1/L2 fusion transcripts can be detected in paraffin-embedded LGFMS in a sensitive manner, using reverse transcription-polymerase chain reaction. Most fusion-positive LGFMS are EMA-positive and CD34/S100/smooth muscle actin negative.

The presence of epithelioid cells and fusion transcripts in both LGFMS and a subset of sclerosing epithelioid fibrosarcoma suggest that these neoplasms might be related.
Molecular Detection of FUS-CREB3L2 Fusion Transcripts in Low-grade Fibromyxoid Sarcoma Using Formalin-fixed, Paraffin-embedded Tissue Specimens.

*Department of Pathology and Oncology, School of Medicine, University of Occupational and Environmental Health daggerDepartment of Pathology, Kyushu Kousei Nenkin Hospital, Kitakyushu double daggerDepartment of Pathology, Nagasaki University Hospital, Nagasaki section signDepartment of Surgical Pathology, School of Medicine, Teikyo University Hospital parallelDepartment of Pathology, NTT MC Kanto Medical Center Division of Pathology, The Jikei Third Hospital, Tokyo #Department of Clinical Research and Laboratory Medicine, Hiroshima Prefectural Hospital, Hiroshima **Pathology Section, Kanazawa University Hospital, Kanazawa daggerdagger
Department of Tumor Pathology, Gunma University Graduate School of Medicine, Gunma double daggerdouble daggerDepartment of Human Pathology, Field of Oncology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima section sign section signDepartment of Surgical Pathology, Fujita Health University Hospital, Toyoake parallel parallelDepartment of Pathology, Saga Prefectural Hospital Koseikan, Saga paragraph sign paragraph signDepartment of Pathology, Kitakyushu Municipal Medical Center, Kitakyushu, Japan.

Am J Surg Pathol. 2006 Sep;30(9):1077-1084. Abstract quote

A diagnosis of low-grade fibromyxoid sarcoma (LGFMS) remains problematic because of its bland-looking histologic features that can be potentially confused with other benign or low-grade fibromyxoid lesions. Recent cytogenetic and molecular analyses have shown that most LGFMSs have a characteristic chromosomal abnormality, t(7;16)(q33;p11), resulting in the FUS-CREB3L2 fusion gene. However, such assays have only rarely been used to analyze formalin-fixed, paraffin-embedded tumor samples.

In the present study, we conducted a reverse transcription-polymerase chain reaction assay to detect the FUS-CREB3L2 fusion transcripts using formalin-fixed, paraffin-embedded tumor tissue specimens from 16 LGFMSs including 3 cases with giant collagen rosettes. The primers were newly designed to specifically amplify most of the junctional regions of the FUS-CREB3L2 fusion gene transcripts previously reported. The FUS-CREB3L2 fusion gene transcripts were detected in 14/16 (88%) cases of LGFMS. A nucleotide sequence analysis of the PCR products revealed that different portions of the FUS exon 6 or 7 were fused with various sites of the CREB3L2 exon 5, resulting in 12 different nucleotide sequences. We also tested a primer set to detect the FUS-CREB3L1 fusion transcript, which is a rare variant of the gene fusion in LGFMS, although no PCR products were identified in any case. The FUS-CREB3L2 fusion transcripts were not detected in any of the 123 other soft-tissue tumors, including desmoid-type fibromatoses, myxofibrosarcomas, soft-tissue perineuriomas, and congenital or adult fibrosarcomas.

These data suggest that our reverse transcription-polymerase chain reaction assay is a reliable method to detect FUS-CREB3L2, which can thus help in accurately diagnosing LGFMS.

Low-grade fibromyxoid sarcoma and hyalinizing spindle cell tumor with giant rosettes share a common t(7;16)(q34;p11) translocation.

Reid R, de Silva MV, Paterson L, Ryan E, Fisher C.

University Department of Pathology/Scottish Bone Tumour Registry Western Infirmary, Glasgow, United Kingdom.
Am J Surg Pathol. 2003 Sep;27(9):1229-36. Abstract quote  

Low-grade fibromyxoid sarcoma (LGFMS) is a rare metastasizing soft tissue tumor with deceptively bland histologic features. The hyalinizing spindle cell tumor with giant rosettes (HSCT) is thought to be a closely related tumor differing only by the presence of collagen rosettes.

We report the occurrence of a common t(7;16)(q34;p11) translocation in 2 cases of HSCT and 2 cases of LGFMS, thereby providing the first cytogenetic proof that LGFMS and HSCT are variants of the same entity. The tumors occurred in the thighs of 2 females and in the buttock and supraclavicular fossa of 2 males. One HSCT had a spectrum of unusual histologic features, including the presence of plump epithelioid cells with abundant cytoplasm and strands and nests of clear epithelioid cells separated by eosinophilic hyalinized stroma. Two cases showed a hitherto unreported, focal staining with epithelial membrane antigen, thus adding to the immunohistochemical profile of these tumors. LGFMS and HSCT probably have a wider spectrum of morphologic features than previously thought, the awareness of which will help pathologists to avoid diagnostic pitfalls.

Demonstration of the t(7;16)(q34;p11) translocation will help to diagnose difficult cases with unusual histologic features.

Low grade fibromyxoid sarcoma. a further low-grade soft tissue malignancy characterized by a ring chromosome.

Mezzelani A, Sozzi G, Nessling M, Riva C, Della Torre G, Testi MA, Azzarelli A, Pierotti MA, Lichter P, Pilotti S.

Department of Pathology and Cytopathology, Istituto Nazionale Tumori, Via G. Venezian 1, 20133, Milan, Italy.

Cancer Genet Cytogenet 2000 Oct 15;122(2):144-8 Abstract quote

Supernumerary rings in the context of a simple karyotype characterize several low-grade malignant tumors of soft tissue and bone. Low-grade fibromyxoid sarcoma is an uncommon low-grade sarcoma, the cytogenetics of which has not yet been reported.

Here we describe the first molecular-cytogenetic characterization of a pulmonary metastasis of low-grade fibromyxoid sarcoma. The histology of the primary and recurrent tumors was consistent with the diagnosis of low-grade fibromyxoid sarcoma of the usual type, whereas the pulmonary metastasis was of the "giant rosettes" variant.

Cytogenetic analysis revealed a ring chromosome. Because gain of material of chromosomes 7 and 16 was detected by CGH, the ring chromosome is assumed to be composed of material from these respective chromosomes.

 

GROSS APPEARANCE/
CLINICAL VARIANTS
CHARACTERIZATION
General

Size range from 1.5-13 cm

Round to oval and well circumscribed with thin pseudocapsule

Firm and fibrous consistency with homogenous cut surface

 

HISTOLOGICAL TYPES CHARACTERIZATION
General

Well circumscribed with thin fibrous pseudocapsule

Two components:fibrous and myxoid with varying grades of cellularity and gradual transitions between the two

Fibrous had spindle cells with linear arrangement producing whorled and swirling growth patterns-occasional herringbone like areas

Myxoid areas with spindle to stellate-shaped cells with abudant intercellular matrix

  Characteristic intranuclear invagination of the cytoplasm, arrangement of the cells into rows, hemosiderin-rich cells, and clefts resembling synovial metaplasia

Low-grade fibromyxoid sarcoma: case report and immunohistochemical study.

Nichols GE, Cooper PH.

Department of Pathology, University of Virginia Health Sciences Center, Charlottesville 22908.

J Cutan Pathol 1994 Aug;21(4):356-62 Abstract quote

A case is presented of low-grade fibromyxoid sarcoma involving the arm of a 52-year-old man.

Low-grade fibromyxoid sarcoma is a recently described neoplasm of the deep and subcutaneous soft tissue which demonstrates a spectrum of histologic images. The current case demonstrated the typical patterns of intermixed, sweeping bands of fibrous and myxoid tissue, homogeneous foci of fibrous and myxoid tissue, focal areas of storiforming, and concentric perivascular cuffs of slender spindle cells, all lacking the nuclear anaplasia, mitotic activity, and necrosis generally associated with sarcoma. Immunohistochemical analysis performed on paraffin-embedded sections demonstrated strong labeling of the tumor cells by anti-CD34 antibody, moderate labeling for vimentin, and rare, focal positivity for muscle-specific actin. Tumor cells were negative for markers of epithelial, muscular, neural, histiocytic, melanocytic, and vascular differentiation.

The constellation of histopathologic features described in this and previous reports is characteristic of low-grade fibromyxoid sarcoma. Based on this case, it appears that the immunohistochemical features of low-grade fibromyxoid sarcoma can help to exclude many cutaneous and deep soft tissue tumors from the differential diagnosis. The findings support the interpretation that the neoplasm is essentially fibroblastic in nature.

Low grade fibromyxoid sarcoma: clinicopathological analysis of eleven new cases in support of a distinct entity.

Goodlad JR, Mentzel T, Fletcher CD.

Department of Histopathology, St Thomas's Hospital, London, UK

Histopathology 1995 Mar;26(3):229-37 Abstract quote

Low grade fibromyxoid sarcoma is a recently recognized, uncommon soft tissue neoplasm with a tendency to develop in deep soft tissue of young adults. Diagnostic criteria have not been well defined and this tumour has not been widely accepted as a distinct entity.

Eleven new cases are reported here for which reproducible histological features are described and in which the immunohistochemical profile of the tumour cells is documented for the first time. Ten of the eleven patients were male and the majority were young or middle-aged adults (median age 45 years). All except one of the tumours were situated in deep soft tissue. Lower limb (four cases) and chest wall (three cases) were the commonest primary sites; one case each arose in the groin, buttock, axilla and retroperitoneum. Follow-up (median duration 6 years) was available in nine patients. Six developed local recurrence and in five cases recurrences were multiple. Pulmonary metastasis occurred in one patient. All tumours were characterized by the presence of bland spindle cells, showing a mainly whorled or focally linear arrangement, set in alternating areas with a fibrous or myxoid stroma. Tumour cells were small, spindle to stellate, with poorly defined, palely eosinophilic cytoplasm and hyperchromatic ovoid nuclei.

Most tumour cells showed strong staining with antibodies to vimentin, while occasional cells stained positively for actin, desmin and cytokeratin, in keeping with focal myofibroblastic differentiation. Ultrastructural examination in one case revealed features of fibroblasts.

Careful consideration of the morphological and immunohistochemical features of these tumours permits a positive diagnosis of low grade fibromyxoid sarcoma and allows its distinction from a number of other benign and malignant soft tissue neoplasms.

Low grade fibromyxoid sarcoma: fine-needle aspiration cytology with histologic, cytogenetic, immunohistochemical, and ultrastructural correlation.

Lindberg GM, Maitra A, Gokaslan ST, Saboorian MH, Albores-Saavedra J.

Department of Pathology, University of Texas Southwestern Medical Center, Dallas 75235, USA.

Cancer 1999 Apr 25;87(2):75-82 Abstract quote

BACKGROUND: Although the histologic features of the recently described low grade fibromyxoid sarcoma are well established, to the authors' knowledge there are no reports in the literature describing the cytologic features of this tumor by fine-needle aspiration. Recognition of this lesion is important because of its indolent but metastasizing nature.

METHODS: The authors retrospectively reviewed their surgical pathology files for cases of low grade fibromyxoid sarcoma with a preoperative fine-needle aspiration biopsy (FNAB); three such cases were found. Immunohistochemical studies were performed in all three tumors, ultrastructural examination was performed in two tumors, and fresh tissue for cytogenetic analysis was obtained in one tumor.

RESULTS: All FNABs showed similar features. The aspirates were relatively hypocellular with an abundant myxoid background; the neoplastic cells contained oval to spindle shaped nuclei with minimal pleomorphism. No capillaries or areas of fibrous tissue were identified. Cytogenetic study of one case revealed no chromosomal abnormalities. The histologic findings were characteristic for this lesion. By immunohistochemistry the tumor cells showed diffuse and strong reactivity for vimentin only; at the ultrastructural level the neoplastic spindle cells had characteristics of fibroblasts.

CONCLUSIONS: The cytologic features of low grade fibromyxoid sarcoma are not specific enough for a definitive diagnosis based on FNAB alone; however, correlating the cytologic and clinical findings can narrow the range of diagnosis. The differential diagnosis includes other myxoid lesions, in particular superficial or intramuscular myxoma and myxofibrosarcoma. In addition, the immunohistochemical and ultrastructural findings support a fibroblastic origin for this neoplasm.

Low-grade fibromyxoid sarcoma: a report of eight cases with histologic, immunohistochemical, and ultrastructural study.

Zamecnik M, Michal M.

Department of Pathology, Slovak Postgraduate Academy of Medicine, Derer's Hospital, Bratislava.

Ann Diagn Pathol 2000 Aug;4(4):207-17 Abstract quote

We present eight cases of low-grade fibromyxoid sarcoma (LGFS) of soft tissues.

The patients, six men and two women, ranged in age from 28 to 44 years (median, 39 years). All tumors were subcutaneous. They were located in the lower extremity (three cases), inguinal/perineal region (two cases), trunk (one case), upper extremity (one case), and neck (one case). Grossly, the lesions were similar to those described in previous studies; fibrous and well circumscribed, with pseudocapsules, and without any necrosis or nodularity. In a single case of hemosiderin-rich tumor, rusty brown strips were seen on the cut surface.

Histologically, the tumors were composed of alternating fibrous and myxoid areas with various cellularity and with swirling and whorled growth patterns. The cells were stellate or spindle shaped and displayed none to mild nuclear pleomorphism and hyperchromasia. Some hypercellular areas showed a fascicular or herring bone pattern similar to common fibrosarcomas. In addition to the known typical picture of LGFS, we also have seen some unusual features. The cells of myxoid areas were often arranged in rows, thus resembling ossifying fibromyxoid tumor or myxoid chondrosarcoma of soft tissues. In a single case, the tumor cells contained a large amount of hemosiderin and the cellular nests contained synovial metaplasia-like clefts. The intranuclear invaginations of cytoplasm represented another interesting finding that was present in all tumors in our series. They seem to be constant or at least frequent features of LGFS, which may assist in the differential diagnosis.

The immunohistochemical and ultrastructural findings were consistent with the fibroblastic nature of LGFS. Four cases also showed features of possible histiocytic modulation of the neoplastic fibroblasts.

Low-Grade Fibromyxoid Sarcoma and Hyalinizing Spindle Cell Tumor With Giant Rosettes A Clinicopathologic Study of 73 Cases Supporting Their Identity and Assessing the Impact of High-Grade Areas

Andrew L. Folpe, M.D.; Kathryn L. Lane, M.D.; Gerson Paull, M.D.; Sharon W. Weiss, M.D.

From the Department of Pathology and Laboratory Medicine, Emory University, Atlanta, Georgia, U.S.A. (A.L.F., G.P., S.WW.); and Huntsville Pathology Associates, Huntsville, Alabama, U.S.A. (K.L.L.).

Am J Surg Pathol 2000;24:1353-1360 Abstract quote

Low-grade fibromyxoid sarcoma (LGFMS) is a rare sarcoma characterized by bland histologic features and a paradoxically aggressive clinical course. The hyalinizing spindle cell tumor with giant rosettes (HSCT) is a closely related tumor characterized by the presence of giant collagen rosettes. Only a single example of a metastasizing HSCT has been reported. A small subset of both LGFMS and HSCT display areas of increased cellularity and atypia which qualify as intermediate-to high-grade sarcoma; the significance of these features has not been definitively assessed.

We present the clinicopathologic features of 77 cases of LGFMS and HSCT to determine the degree of overlap of these two lesions, their biologic behavior, and the significance of the occasional presence of intermediate-to high-grade sarcoma within both.

The patients (33 female, 40 male) ranged from 3 to 78 years of age (median, 34 yrs). Fourteen cases occurred in patients less than 18 years of age. The tumors measured from 1 to 23 cm (median, 4.5 cm) and occurred predominantly in the trunk and lower extremities in both the deep (66 cases) and superficial (7 cases) soft tissues. In 15 cases, the tumor was present >1 year before diagnosis. All tumors showed predominantly the typical hypocellularity and bland cytologic features of typical LGFMS; however, areas of hypercellularity and nuclear enlargement and hyperchromatism were identified in 12 of 73 (16%) and 7 of 73 (10%), respectively. Necrosis and mitotic activity >5/50 high-powered fields (HPF) were present in 6 of 73 (8%) and 5 of 73 (7%), respectively. Epithelioid areas were present in 33 of 73 (45%) and rosettes in 22 of 73 (30%). Follow up (54 cases; range, 2192 mos; median, 24 mos; mean, 38 mos) showed 5 recurrences, 3 metastases, and 1 death. The diagnosis of LGFMS or HSCT was made prospectively in 51 patients; none had metastatic disease. Two of the metastatic tumors were LGFMS and one was a HSCT. LGFMS may occur more often in the pediatric population and show a much wider histologic spectrum than previously thought. A significant number of LGFMS possess inconspicuous collagen rosettes characteristic of HSCT, indicating that these two tumors are ends of a common spectrum rather than distinct entities.

HSCT, like LGFMS, are low-grade sarcomas with metastatic potential. The presence of focal areas of intermediate-to high-grade sarcoma does not portend a worse outcome in the short term. The better prognosis reflected in this study compared with previous ones might reflect the fact that all were initially diagnosed as sarcomas and treated with aggressive surgery. The fact that the only three patients to develop metastatic disease were patients whose LGFMS or HSCT was identified retrospectively supports this concept.

SUPERFICIAL  
Superficial Low-grade Fibromyxoid Sarcoma (Evans Tumor): A Clinicopathologic Analysis of 19 Cases With a Unique Observation in the Pediatric Population.

Billings SD, Giblen G, Fanburg-Smith JC.

From the *Departments of Pathology and Laboratory Medicine and Dermatology, Indiana University School of Medicine, Indianapolis, IN; daggerDepartment of Pathology, Georgetown University, Washington, DC; and double daggerDepartment of Soft Tissue Pathology, Armed Forces Institute of Pathology, Washington, DC.
Am J Surg Pathol. 2005 Feb;29(2):204-210. Abstract quote

Low-grade fibromyxoid sarcoma (LGFMS), usually a deeply situated mass in adults, is uncommon in superficial soft tissue and in children.

Nineteen superficial LGFMS from our files were studied for clinicopathologic features, the latter including tumor size, growth pattern, cellularity, collagen rosettes, vascularity, nuclear atypia, mitotic rate, necrosis, and immunophenotype. The patients included 12 males and 7 females who ranged in age from 2 to 70 years (mean, 29 years). There were 7 children. Tumor locations included the lower extremity (8), buttock (3), trunk (3), vulva/inguinal region (2), upper extremity (2), and unspecified subcutis (1). Clinical and histologic submitting diagnoses were mainly benign except for 3 cases, submitted as low-grade sarcoma, with only one as superficial LGFMS. The mean tumor size was 4.2 cm (range, 1.6-18 cm). Of 15 with evaluable resections, 5 had focal ink on tumor and 2 of these had known negative wider reexcisions. The tumors were relatively well circumscribed with low to moderate cellularity. The tumors alternated from myxoid zones with prominent curvilinear vasculature to collagenous fascicular zones. Collagen rosettes with peripheral round epithelioid cells and focal ischemic necrosis were present in 6 cases each. Mitotic rate was low (mean 1.6/50 HPF).

Tumor cells were positive for vimentin and some were focally positive for actins, CD68, and EMA. CD34, keratins, and S-100 protein were negative. Follow-up (mean, 44 months; range, 10-84 months) on 16 patients demonstrated 14 with no evidence for disease, 2 with local recurrences at 5 and 16 months, but no metastases.

Superficial LGFMS is more common than previously recognized and may affect children at a higher rate (7 of 19, 37%) than that for deep LGFMS. The prognosis is good and appears to be better than that for deep LGFMS.

 

SPECIAL STAINS/
IMMUNO-PEROXIDASE
CHARACTERIZATION
Vimentin Positive
Negative S100, SMA, CK, EMA, CD34

A case of low-grade fibromyxoid sarcoma of the thigh.

Ugai K, Kizaki T, Morimoto K, Sashikata T.

Division of Pathobiology, College of Nursing Art and Science Hyogo, Akashi, Japan.

Pathol Int 1994 Oct-Nov;44(10-11):793-9 Abstract quote

A case of low-grade fibromyxoid sarcoma in the thigh of a 21 year old female is described.

The patient had a fist-sized well-defined mass in her left thigh that enlarged over a 6 month period. Histologically, the neoplasm showed contrasting fibrous and myxoid areas with a swirling growth pattern. Cellularity was low to moderate, and the stromal cells were benign looking without mitoses or nuclear pleomorphism. The tissue was not noticeably vascular. Some stromal cells were aggregated around the blood vessels.

The stromal cells were immunoreactive to vimentin, but were negative to keratin, desmin, alpha-smooth muscle actin, actin HHF35, S-100 protein, neuron-specific enolase, and epithelial membrane antigen. Ultrastructural examinations of the stromal cells revealed well-developed rough endoplasmic reticulum, mitochondria, pinocytotic vesicles, and numerous intermediate-sized filaments in the cytoplasm. These findings seem to indicate that the stromal cells were fibroblastic in origin. The occurrence of the tumor in a young adult, its location and its large, well defined borders together with the characteristics revealed through histological investigation, indicated that it was in fact what has been termed by Evans as a low-grade fibromyxoid sarcoma.

Low-grade fibromyxoid sarcoma.

Fukunaga M, Ushigome S, Fukunaga N.

Department of Pathology, Jikei University School of Medicine, Tokyo, Japan.

Virchows Arch 1996 Nov;429(4-5):301-3 Abstract quote

A low-grade fibromyxoid sarcoma arising in the thigh of a 16-year-old Japanese girl is described. The patient had a well-circumscribed mass measuring 3.5 cm in its greatest diameter within her left vastus medialis muscle and a 6-month history of pain.

Microscopically, the tumour was not encapsulated and filtrated into adjacent skeletal muscle. The tumour was characterized by poor to moderate cellularity, a proliferation of bland-appearing spindle tumour cells, and alternating fibrous and myxoid areas with a whorled pattern of the tumour cells. Neither cellular atypia nor mitotic figures were observed. There was no tumour necrosis.

Immunohistochemically, the tumour cells were diffusely and strongly positive for vimentin and desmin. Some cells contained alpha smooth muscle actin. They were uniformly negative for CAM5.2, epithelial membrane antigen, muscle-specific actin (HHF35), factor-VIII-related antigen, S-100 protein, neurofilament, CD34, and CD31. The tumour had a diploid DNA content with S-phase fractions of 6.6% by flow cytometry. The patient was alive with no evidence of disease 11 months after excision.

 

DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES

Hyalinizing spindle cell tumor with giant rosettes: a distinctive tumor closely resembling low-grade fibromyxoid sarcoma.

Lane KL, Shannon RJ, Weiss SW.

Department of Pathology, University of Michigan Hospitals, Ann Arbor 48109-0054, USA

Am J Surg Pathol 1997 Dec;21(12):1481-8 Abstract quote

We report the findings of 19 cases of a previously undescribed spindle cell tumor of soft tissues that resembles a low-grade fibromyxoid sarcoma but contains distinctive rosettelike structures.

The tumors occurred principally as a painless, slowly growing, deeply situated mass of the proximal extremities in young to middle-aged adults (age range 14-65 years; mean 38). Although grossly circumscribed, the tumors had infiltrative borders microscopically and were composed of bland spindled cells situated in a hyalinized to myxoid stroma.

The most characteristic feature of the tumor was scattered large rosettelike structures that often merged with serpinginous areas of dense hyalinization. The rosettes consisted of a central collagen core surrounded by a rim of rounded cells morphologically and immunophenotypically different from the cells of the spindled stroma. These cells expressed a number of antigens, including S-100 protein, neuron-specific enolase, and leu 22, in contrast to the stroma, which usually lacked these antigens. Of the 12 patients with available follow-up information, one patient treated with simple excision clinically developed local recurrence of the tumor 20 months after initial biopsy. No other recurrences were reported during the limited follow-up period, and no patient developed metastatic disease. However, the favorable prognosis of the patients in our series to date may relate to the limited follow-up period (approximately 3 years), as well as initial treatment by wide excision in nearly half of the patients.

We regard the hyalinizing spindle cell tumor with giant rosettes as a distinctive type of low-grade fibroblastic tumor that with time may prove to behave similar to a low-grade fibromyxoid sarcoma and, hence, to represent an unusual variant thereof.

 

PROGNOSIS AND TREATMENT CHARACTERIZATION
PROGNOSIS Rare with some tumors showing low grade features and others showing hyalinizing spindle cell tumor with rosettes

Low-grade fibromyxoid sarcoma. A report of two metastasizing neoplasms having a deceptively benign appearance.

Evans HL.

Department of Pathology, University of Texas M.D. Anderson Hospital, Houston 77030.

Am J Clin Pathol 1987 Nov;88(5):615-9 Abstract quote

Two deceptively benign-appearing, unclassifiable but very similar fibromyxoid sarcomas characterized histologically by bland, innocuous-appearing fibroblastic cells and a swirling, whorled growth pattern are presented.

The tumors both occurred in women in their late twenties and were located in the soft tissues of the scapular area and the axillary-chest wall area, respectively. Lung metastases developed in both cases; one patient died 94 months after excision of the primary neoplasm, whereas the other was alive at 82 months.

The designation "low-grade fibromyxoid sarcoma" is suggested for these tumors.

Low-grade fibromyxoid sarcoma. A report of 12 cases.

Evans HL.

Department of Pathology, University of Texas M.D. Anderson Cancer Center, Houston 77030.

Am J Surg Pathol 1993 Jun;17(6):595-600 Abstract quote

Twelve cases of low-grade fibromyxoid sarcoma are presented.

The patients' ages ranged from 6 to 51 years; all but three were between 26 and 46 years of age. The tumor was located in the thigh or inguinal area in four patients, in the shoulder area in three patients, and in the axilla-chest wall area, the perineum, the small bowel mesentery, the neck, and the buttock in one patient each. Tumor size (maximum dimension) varied from 3.5 to 15 cm in the nine cases in which it was known (median, 9.5 cm). Histologically, the neoplasms demonstrated contrasting fibrous and myxoid areas, a swirling, whorled growth pattern (at least in part), and bland, deceptively benign-appearing fibroblastic spindle cells; cellularity was low to moderate, mitotic figures were uncommon, and nuclear pleomorphism was usually absent or slight. Focal histologic findings in a minority of the cases included increased perivascular cellularity, moderate nuclear pleomorphism (more often in recurrent tumors), and, in myxoid areas, a rich capillary vascular network (vascularity was usually not prominent).

On follow-up, nine patients experienced local recurrence (from one to numerous times); recurrence was subsequently controlled in five cases but not in the remaining four. Distant metastasis occurred in seven cases, chiefly to the lungs, but two of these patients were rendered tumor-free (to latest follow-up) by excision of metastases. At latest follow-up, four patients had died of tumor at 8, 9, 31, and 31 1/2 years, respectively, three were alive with recurrent or metastatic tumor at 6 1/2, 12 1/2, and 50 years, respectively, and five were alive and tumor-free at 5 1/2, 10 1/2, 12, 22 1/2, and 44 years, respectively. One tumor, in the patient who died at 31 years, demonstrated "dedifferentiation" at 30 years. Low-grade fibromyxoid sarcoma is a distinctive, indolent soft-tissue sarcoma.

Low-grade fibromyxoid sarcoma: clinicopathologic case report with review of the literature.

Shidham VB, Ayala GE, Lahaniatis JE, Garcia FU.

Department of Surgical Pathology, Medical College of Wisconsin, Milwaukee 53226, USA.

Am J Clin Oncol 1999 Apr;22(2):150-5 Abstract quote

Low-grade fibromyxoid sarcoma is a rare, benign-appearing soft tissue neoplasm with an aggressive clinical course characterized by multiple local recurrences over several years, with ultimate spread to lung and occasionally to bone. Thus far, a total of 24 cases of low-grade fibromyxoid sarcoma have been reported in the literature.

The authors present an additional case that grossly and microscopically emphasizes a pronounced lobular pattern of contrasting areas of cellularity showing high proliferative activity, as demonstrated by a proliferation marker, Ki 67 with MIB-1, and hypocellular areas with prominent myxoid component and abundant collagen fibrils. There was predominance of delicate capillary-sized stromal vessels with collagenized walls in both cellular and myxoid areas. The unusual features in this case were osseous metaplasia, prominent intranuclear pseudoinclusions, DNA tetraploidy, and membrane-bound intracytoplasmic fat vacuoles. The immunoprofile and cytologic and ultrastructural features are described.

After the excision of the tumor, the patient was treated with radiotherapy without chemotherapy. The patient has been observed for 26 months and is alive without the evidence of disease. The postoperative follow-up with axial computed tomography at 24 months showed no evidence of disease, except postsurgical fibrotic changes.

Low-grade fibrosarcoma with palisaded granulomalike bodies (giant rosettes): report of a case that metastasized.

Woodruff JM, Antonescu CR, Erlandson RA, Boland PJ.

Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York, New York 10021, USA

Am J Surg Pathol 1999 Nov;23(11):1423-8 Abstract quote

"Hyalinizing spindle cell tumor with giant rosettes" is a tumor recently described by Lane et al. and thought by them possibly to represent a form of low-grade fibromyxoid sarcoma. Proof of a metastatic potential was lacking. We report an example of this tumor on the arm of a 28-year-old woman. The ultrastructural study of the tumor confirmed the fibroblastic nature of the lesion, which subsequently metastasized to the lung. Histologically, the giant rosettes simulated palisaded granulomas.

Our findings warrant classifying the tumor as a sarcoma, and we suggest the designation low-grade fibrosarcoma with palisaded granulomalike bodies (giant rosettes).

Low-grade fibromyxoid sarcoma.

van den Bossche MR, Van Mieghem H.

Department of Abdominal Surgery, Sint-Elisabeth Hospital, Brussels, Belgium.

Oncology 2000 Apr;58(3):207-9 Abstract quote

Described is a low-grade fibromyxoid sarcoma (LGFMS) of the abdominal wall muscles in a 38-year-old black woman. There was no evidence of metastatic disease. A 5.2-kg LGFMS - the largest case ever reported - was resected. One year after surgery, the patient is alive without any sign of local recurrence or distant metastasis.

Follow-up comprises abdominal and thoracic CT scans at 6-month intervals.

TREATMENT Excision

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