Trichoepitheliomas are hamartomas arising from hair follicular epithelium.
They have a characteristic intimate association of the epithelium and mesenchyme.
The characteristic structure, under the microscope, the papillary-mesenchymal
body. This is a recapitulation of a primitive hair bulb. It is benign but
must be distinguished from a basal cell carcinoma.
GROSS APPEARANCE/
CLINICAL
VARIANTS |
CHARACTERIZATION |
| General |
|
| VARIANTS |
|
| FAMILIAL |
|
|
Solitary familial desmoplastic trichoepithelioma. A study by conventional
and electron microscopy.
Dervan PA, O'Hegarty M, O'Loughlin S, Corrigan T.
|
Am J Dermatopathol 1985 Jun;7(3):277-82 Abstract quote
Solitary desmoplastic trichoepitheliomas from a mother and two daughters
were studied by conventional and electron microscopy.
Differential diagnosis by conventional microscopy is briefly discussed.
The lesions consisted of cords and nests of basaloid cells set in fibrotic
stroma and confined to the dermis. In addition, each lesion contained
horn cysts and focal areas of calcification. Horn cysts were occasionally
identified in continuity with infundibulae of normal hair follicles.
Semithin sections showed cords and nests of cells in continuity with
the horn cysts. Ultrastructurally, a continuous basal lamina surrounded
the cords of basaloid cells and connected to horn cysts. Individual
cells contained tonofilaments and were attached to adjacent cells by
desmosomes. Hemidesmosomes were present at peripheral cell membranes
bounded by basal lamina. There was no glandular differentiation.
Our observations by electron and conventional microscopy support a
conclusion that desmoplastic trichoepitheliomas are derived from hair
appendages.
|
|
Multiple familial trichoepitheliomas: a folliculosebaceous-apocrine
genodermatosis.
Clarke J, Ioffreda M, Helm KF.
|
Am J Dermatopathol 2002 Oct;24(5):402-5 Abstract quote
We reviewed the pathologic findings on a family with multiple hereditary
trichoepitheliomas. Although the majority of the lesions were trichoepitheliomas,
basal cell carcinomas, spiradenomas, and spiradenomas with cylindromatous
foci (spiradenocylindroma) were present, representing a spectrum of
lesions exhibiting folliculosebaceous (trichoepithelioma, basal cell
carcinoma) and apocrine (spiradenoma, spiradenocylindroma) differentiation.
Multiple familial trichoepitheliomas may be a syndrome whereby tumors
develop from undifferentiated germinative cells of the folliculosebaceous-apocrine
unit. Published findings regarding the genetics of this syndrome and
solitary trichoepitheliomas are reviewed; although the molecular basis
for the tumors has yet to be determined, current data suggest that a
tumor suppressor gene may be involved.
|
| VULVA |
|
|
Trichoepithelioma of the vulva. A report of two cases.
Cho D, Woodruff JD.
Department of Gynecology and Obstetrics, Johns Hopkins Hospital,
Baltimore, Maryland
|
J Reprod Med 1988 Mar;33(3):317-9 Abstract quote
Trichoepithelioma usually presents clinically as single or multiple
nodules on the face, scalp, neck and trunk, and no cases of it on the
vulva have been described before. Vulvar trichoepithelioma has complex
histologic patterns and originates in appendages that simulate malignancy.
|
| HISTOLOGICAL TYPES |
CHARACTERIZATION |
| GENERAL |
|
|
Papillary mesenchymal bodies: a histologic finding useful in differentiating
trichoepitheliomas from basal cell carcinomas.
Brooke JD, Fitzpatrick JE, Golitz LE.
Department of Pathology, Fitzsimons Army Medical Center, Aurora,
CO 80045-5000.
|
J Am Acad Dermatol 1989 Sep;21(3 Pt 1):523-8 Abstract quote
To distinguish a basal cell carcinoma (BCC) from a trichoepithelioma
can be difficult even for an experienced dermatopathologist. Previously
reported differentiating histologic features are relative criteria that
may be shared by both tumors.
In a review of 30 consecutive cases each of trichoepitheliomas, keratotic
BCC, and routine BCC, classic criteria were compared with papillary
mesenchymal body formation. Papillary mesenchymal bodies are distinct
fibroblastic aggregations that represent abortive attempts to form the
papillary mesenchyme responsible for hair induction. Papillary mesenchymal
bodies were observed in 93% of all trichoepitheliomas, 7% of all keratotic
BCC, and 0% of all routine BCC. Hair bulb formation was observed in
30% of trichoepitheliomas and in none of the BCC.
We conclude that papillary mesenchymal body formation is an easily
recognizable histologic criterion that is more reliable in differentiating
these two tumors than standard criteria, including epidermal connections,
keratinization, calcification, foreign body reaction, fibrosis, stromal
retraction, tumor mucin, ulceration, frondlike epithelial pattern, and
the inflammatory response.
|
| VARIANTS |
|
| AMYLOID |
|
|
Secondary localized amyloidosis in trichoepithelioma. A light microscopic
and ultrastructural study.
Lee YS, Fong PH. Department of Pathology and Medicine, National
University of Singapore, Republic of Singapore.
|
Am J Dermatopathol 1990 Oct;12(5):469-78 Abstract quote
Two trichoepitheliomas with secondary localized amyloidosis were documented
in a 74-year-old man. The ultrastructural findings support an origin
of amyloid from tumor cells. It is suggested that the occurrence of
amyloid is a reflection of the ability of tumor cells to produce an
excessive number of tonofilaments from which amyloid is believed to
be derived.
The intimate spatial association between amyloid and fibroblasts may
suggest the existence of some yet undefined functional relationship.
|
| BLUE NEVUS |
|
|
Blue naevus associated with trichoepithelioma: a report of two cases.
Newton JA, McGibbon DH.
|
Cutan Pathol 1984 Dec;11(6):549-52 Abstract quote
Naevocellular naevi may show considerable histological variation and
have often been shown to contain other ectodermal elements, as well
as cells of melanocytic origin. Blue naevi are also thought to be of
melanocytic origin, and in this report we describe two blue naevi in
which trichoepitheliomatous elements were seen.
The aetiological implications of this observation are discussed.
|
| CYSTIC |
|
|
Cystic giant solitary trichoepithelioma.
Lorenzo MJ, Yebra-Pimentel MT, Peteiro C, Toribio J.
Department of Dermatology, General Hospital of Galicia, Faculty
of Medicine, Santiago de Compostela, Spain.
|
Am J Dermatopathol 1992 Apr;14(2):155-60 Abstract quote
A case of a giant solitary trichoepithelioma is reported. The tumor
was located on the thigh, extending from the deep dermis to the subcutaneous
tissue with no epidermal contact, and showed a large central cystic
cavity that measured 9 cm x 4 cm.
We review the cases published under this and other names.
|
| DESMOPLASTIC |
|
|
Desmoplastic trichoepithelioma and intradermal nevus: a combined malformation.
Brownstein MH, Starink TM.
Laboratory of Dermatopathology, Port Washington, NY 11050.
|
J Am Acad Dermatol 1987 Sep;17(3):489-92 Abstract quote
We studied 13 desmoplastic trichoepitheliomas associated with intradermal
nevi. Ten intradermal nevi were found among 76 new cases of desmoplastic
trichoepithelioma (13%); three additional examples of the combined malformation
were seen in consultation. Clinically, desmoplastic trichoepithelioma
associated with an intradermal nevus was typically a small, firm or
hard, sometimes annular, nodule on the face, particularly the cheek,
of a relatively young woman.
Microscopically, the combined malformation contained narrow strands
of basaloid cells and keratinous cysts in a desmoplastic stroma, intimately
mixed with intradermal nests of nevocytes. Melanocytic nevi have been
associated with epidermal hyperplasia resembling seborrheic keratoses,
follicular cysts, trichostasis spinulosa, syringomas, basal cell carcinomas,
and hair follicle formation on the soles.
The frequency of the occurrence of intradermal nevus with desmoplastic
trichoepithelioma and the close anatomic association of the two elements
may indicate that this combined malformation is another example of epithelial
induction by melanocytic nevi.
|
|
Merkel cells are integral constituents of desmoplastic trichoepithelioma:
an immunohistochemical and electron microscopic study.
Hartschuh W, Schulz T.
Department of Dermatology, University of Heidelberg, Germany.
|
J Cutan Pathol 1995 Oct;22(5):413-21 Abstract quote
The incidence of Merkel cells has previously been investigated in a
number of inflammatory and tumorous lesions of the skin. Special attention
was given to tumors with follicular differentiation. In the present
study we examined the localization of Merkel cells in another adnexal
tumor, the desmoplastic trichoepithelioma (n = 15), as well as in its
main differential diagnosis, the morpheiform basal-cell carcinoma (n
= 30).
Using immunohistochemical methods, we found Merkel cells as a stable
constituent in desmoplastic trichoepitheliomas, but failed to detect
them in morpheiform basal-cell carcinomas. These findings might therefore
be an important tool in the sometimes very difficult but clinically
imperative distinction between these two conditions. Furthermore, our
study may be of interest in the discussion about the origin of desmoplastic
trichoepitheliomas. High numbers of Merkel cells in desmoplastic trichoepitheliomas
indicate a bulge-derived origin of this adnexal tumor, since high numbers
of Merkel cells, especially in the bulge, were recently discovered.
Although the significance of Merkel cell hyperplasia in desmoplastic
trichoepithelioma is not presently understood, a regulatory role of
the Merkel cell in growth and development of this adnexal tumor is suggested.
|
|
Desmoplastic trichoepithelioma of the upper lip. A case report with
histochemical features and observations on its histogenesis.
Triantafyllou A, Scott J, Blacklock A.
Academic Unit of Oral Diseases, University of Liverpool School of
Dentistry, UK.
|
Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995 Oct;80(4):445-50
Abstract quote
A case of desmoplastic trichoepithelioma of the upper lip investigated
by histochemistry and immunocytochemistry is presented. There was histologic
suggestion of cytoplasmic vacuolation that does not appear to have been
previously described.
Histochemical examination indicated the presence of glycogen within
tumor cells and a reparative-type stroma. Immunocytochemical examination
revealed variable reactivity for high molecular weight cytokeratin and
colonization by Langerhans' cells. The observations suggest a follicular
and sudoriferous differentiation for desmoplastic trichoepithelioma
and hence an origin from a pluripotential adnexal keratinocyte.
|
|
Desmoplastic trichoepithelioma.
Zuccati G, Massi D, Mastrolorenzo A, Urbano FG, Paoli S, Reali UM.
Istituto di Clinica Dermosifilopatica, Universita degli Studi di
Firenze, Florence, Italy.
|
Australas J Dermatol 1998 Nov;39(4):273-4 Abstract quote
A 20-year-old male presented with a 4 year history of a solitary nodule,
8 mm in diameter on the left temple. It was covered by normal skin,
with a central depression and elevated borders. Histopathology showed
numerous horn cysts amidst nests and strands of basaloid cells surrounded
by a dense fibrous stroma.
The clinical and histopathological features were characteristic of
desmoplastic trichoepithelioma.
|
| IMMATURE |
|
|
Immature trichoepithelioma: report of six cases.
Long SA, Hurt MA, Santa Cruz DJ.
Department of Pathology, St. John's Mercy Medical Center, St. Louis,
Missouri
|
J Cutan Pathol 1988 Dec;15(6):353-8 Abstract quote
We report 6 cases of an immature variant of trichoepithelioma which
histologically appears to show differentiation toward the primitive
hair germ. The lesions presented in mature adults (mean age 44 years).
Four occurred in men and 2 in women. Four lesions occurred on extremities,
an unusual location for trichoepitheliomas. Histologically, the lesions
were characterized by well-circumscribed, but unencapsulated, dermal
collections of small tumor lobules composed of basaloid cells with invaginations
resembling primitive dermal hair papillae. There was no adenoidal growth
pattern or horn cyst formation. The separation of the immature lesions
from those of classical trichoepithelioma and basal cell carcinoma can
be made if multiple morphological features are considered; no one particular
finding is diagnostic. The major differential features between the immature
trichoepithelioma and basal cell carcinoma are circumscription, tumor
lobule uniformity, occasional immature hair germs, and lack of retraction
artifact of the tumor lobules from the stroma. The differential features
between the immature and classical trichoepithelioma are less conspicuous.
The immature form typically exhibits no horn cysts, displays fewer
primitive hair structures, and lacks the adenoidal growth patterns of
the tumor lobules which are usually present in the classical trichoepitheliomas.
|
| MELANOCYTIC NEVUS |
|
|
Desmoplastic trichoepithelioma and intradermal nevus: a combined
malformation.
Brownstein MH, Starink TM.
Laboratory of Dermatopathology, Port Washington, NY
|
J Am Acad Dermatol 1987 Sep;17(3):489-92 Abstract quote
We studied 13 desmoplastic trichoepitheliomas associated with intradermal
nevi.
Ten intradermal nevi were found among 76 new cases of desmoplastic
trichoepithelioma (13%); three additional examples of the combined malformation
were seen in consultation. Clinically, desmoplastic trichoepithelioma
associated with an intradermal nevus was typically a small, firm or
hard, sometimes annular, nodule on the face, particularly the cheek,
of a relatively young woman.
Microscopically, the combined malformation contained narrow strands
of basaloid cells and keratinous cysts in a desmoplastic stroma, intimately
mixed with intradermal nests of nevocytes. Melanocytic nevi have been
associated with epidermal hyperplasia resembling seborrheic keratoses,
follicular cysts, trichostasis spinulosa, syringomas, basal cell carcinomas,
and hair follicle formation on the soles.
The frequency of the occurrence of intradermal nevus with desmoplastic
trichoepithelioma and the close anatomic association of the two elements
may indicate that this combined malformation is another example of epithelial
induction by melanocytic nevi.
|
| MONSTER STROMAL CELLS |
|
|
Trichoepithelioma with "monster" stromal cells.
Rivet J, Rogez C, Wechsler J.
Department of Pathology, Hospital Saint Louis, Paris, France.
|
J Cutan Pathol 2001 Aug;28(7):379-82 Abstract quote
Trichoepithelioma is a benign tumor of trichogenic origin which appears
predominantly in childhood or in young adults. Different forms have
been described according to clinical and histological features.
The authors report a unique variant of trichoepithelioma arising on
the limb of a 27-year-old man. The tumor was characterized by the mixture
of an atypical fibroxanthomatous proliferation and basaloid epithelial
strands of trichoepithelioma. Such histological features have not been
previously reported.
It raises the question of an additional variant of hair follicle tumor
with a mixed epithelial and mesenchymal proliferation.
|
SPECIAL STAINS/
IMMUNOPEROXIDASE/
OTHER |
CHARACTERIZATION |
| Special stains |
|
| Immunoperoxidase |
|
| DESMOPLASTIC |
|
|
Immunohistochemical and ultrastructural observations of desmoplastic
trichoepithelioma with a special reference to a morphological comparison
with normal apocrine acrosyringeum
Osamu Yamamoto
Tetsuo Hamada
Yoshiaki Doi
Yasuyuki Sasaguri
Hiroshi Hashimoto
|
J Cutan Pathol 2002;29:15 Abstract quote
Background: Desmoplastic trichoepithelioma is a benign neoplasm considered
to have follicular differentiation. Its sweat gland- or sebaceous-lines
of differentiation have been also reported. There have been, however,
only a few reports regarding extensive immunohistochemical and ultrastructural
investigations of this neoplasm.
Methods: Histopathological and immunohistochemical studies were performed
on three cases of desmoplastic trichoepithelioma, comparing it with
normal skin. One of these cases was ultrastructurally investigated.
Results: The cord-like basaloid nests were reacted with the anti-cytokeratin
(CK)1/5/10/14, -CK5/8, -CK14 and -CK15 antibodies, but not with the
anti-CK6 antibody. Similar findings were observed in the outer layers
of the normal follicular outer root sheath. Basaloid cell nests in one
case, which showed ductal structures in the nests, also expressed CK7,
CK8/18 and CK19. These keratins were also detected in the normal sweat
glands. In addition, CK8/18 and CK19 were expressed in the basal cells
of the outer root sheath. Keratinous cysts had inner reactions with
the anti-CK10/11 and -CK6 antibodies, and outer reactions with anti-CK5/8
and -CK14 antibodies. Ultrastructurally, the cells in the cord-like
nests were basically immature and basaloid in appearance. A few cells
contained Odland bodies, which were also observed in the normal apocrine
acrosyringeum. The ductal structure was lined by the cells which bore
numerous microvilli in the luminal surface.
Conclusion: The cells in desmoplastic trichoepithelioma are suggested
to be in close association with the basal cells in the outer root sheath,
which can differentiate into various parts of the folliculosebaceous
apocrine unit.
|
| GENERAL |
|
| ANDROGEN RECEPTOR |
|
-
Androgen receptor expression helps to differentiate basal cell carcinoma from benign trichoblastic tumors.
Izikson L, Bhan A, Zembowicz A.
Department of Dermatology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
|
-
| Am J Dermatopathol. 2005 Apr;27(2):91-5. Abstract quote |
|
Histologic differentiation between basal cell carcinoma and benign trichoblastic neoplasms such as trichoepithelioma and trichoblastoma can be difficult on small biopsies. Therefore, several attempts have been made to identify immunohistochemical differences between these entities. Recent studies have shown androgen receptor expression in a number of mature epithelial structures in the skin and in epithelial neoplasms including basal cell carcinoma. In contrast, androgen receptor expression was absent in mature hair follicles or the few trichogenic neoplasms studied to date. These findings suggested that androgen receptor expression might be a useful adjunct in the histologic differential diagnosis between basal cell carcinoma and benign trichoblastic neoplasms.
Therefore, we performed immunohistochemical analysis of androgen receptor expression in 32 basal cell carcinomas and 10 benign trichoblastic tumors (6 trichoepitheliomas and 4 trichoblastomas). In our study, at least focal expression of androgen receptor was detected in 78% of basal cell carcinomas. None of the trichoblastic tumors showed any androgen receptor immunoreactivity.
These results confirm the lack of expression of androgen receptor in benign trichoblastic neoplasms and indicate that androgen receptor expression by tumor cells points to basal cell carcinoma as the most likely diagnosis.
|
| CD34 |
|
|
CD34 staining pattern distinguishes basal cell carcinoma from trichoepithelioma.
Kirchmann TT, Prieto VG, Smoller BR.
Department of Dermatology, Stanford University Medical Center, Calif.
|
Arch Dermatol 1994 May;130(5):589-92 Abstract quote
BACKGROUND AND DESIGN: Trichoepithelioma is a benign skin tumor with
follicular differentiation, which sometimes is difficult to distinguish
clinically and histologically from basal cell carcinoma. One of the
most helpful differences is the histologic appearance of the stroma.
CD34 is an antigen known to stain the spindle-shaped cells located around
the middle portion of normal hair follicles. We have stained formalin-fixed,
paraffin-embedded sections of 16 trichoepitheliomas and 19 basal cell
carcinomas for CD34 (anti-HPCA-1, Becton Dickinson, San Jose, Calif)
to detect differences in the staining pattern and to facilitate discrimination
of these two types of tumors.
RESULTS: The spindle-shaped cells surrounding the islands of trichoepithelioma
cells were focally strongly positive for CD34. In all basal cell carcinomas,
the spindle-shaped cells surrounding the nests of tumor cells were negative;
in these areas only the blood vessels were positive with this antibody.
CONCLUSIONS: CD34 staining pattern differentiates between trichoepithelioma
and basal cell carcinoma. CD34 stain may be helpful in distinguishing
between these two tumors on small punch biopsies or in difficult diagnostic
cases.
|
|
Immunohistologic differential diagnosis of basal cell carcinoma,
squamous cell carcinoma, and trichoepithelioma in small cutaneous biopsy
specimens.
Swanson PE, Fitzpatrick MM, Ritter JH, Glusac EJ, Wick MR.
Division of Dermatopathology, Washington University School of Medicine,
St. Louis, Missouri, USA.
|
J Cutan Pathol 1998 Mar;25(3):153-9 Abstract quote
The distinction between squamoid basal cell carcinoma and basaloid
squamous cell carcinoma (or between BCC and trichoepithelioma variants)
is usually made readily on the basis of defined histological criteria.
However, these differential diagnoses occasionally can pose difficult
morphological problems. The stated distinctions are clinically important
because the risk of progressive disease is significantly higher with
squamous carcinoma of the skin than with basal cell carcinoma (BCC),
and a trichoepithelioma misinterpreted as BCC burdens the patient with
an inaccurate diagnosis that may result in inappropriate surgery. Recent
reports have suggested that reactivity with the monoclonal antibody
Ber-EP4 is capable of separating histologically similar basal cell and
squamous carcinomas, and that the expression of bcl-2 or CD34 antigen
is able to distinguish BCC from trichoepithelioma. However, corroborative
studies of these contentions are few in number.
In order to investigate the usefulness of the stated immunostains
in the above-cited differential diagnoses, the authors analyzed 45 basal
cell carcinomas and 22 squamous carcinomas, as well as 36 trichoepitheliomas.
The monoclonal antibodies Ber-EP4, My10 (CD34), and anti-bcl-2 were
applied to formalin-fixed paraffin sections in all cases, using a standard
avidin-biotin-peroxidase complex method. Most BCCs demonstrated strong,
diffuse cytoplasmic labeling with Ber-EP4 and anti-bcl-2. In contrast,
the squamous carcinomas were uniformly negative for the former marker
and only focally reactive for the latter in four examples. 'Peripheral'
bcl-2 staining of trichoepitheliomas was noted in 24 of 33 of the immunoreactive
tumors, but the remainder were marked diffusely and similarly to most
BCCs. Among the latter, immature trichoepitheliomas were diffusely reactive
for this marker in 6 of 8 cases. Labeling of epithelium for CD34 failed
to discriminate between any of the tumor types under evaluation, whereas
staining of peritumoral stroma was characteristic of the majority of
trichoepitheliomas and more than one-third of metatypical basal cell
carcinomas.
These data support the suggestion that Ber-EP4 and bcl-2 are useful
in the separation of BCC from squamous carcinomas. Nevertheless, they
also serve to caution against reliance upon bcl-2 and CD34 immunostains
in attempting to distinguish BCC from trichoepithelioma in histologically
enigmatic cases. There is currently no certain method other than conventional
microscopy that can be applied successfully to the latter problem.
|
|
An immunohistochemical study of basal cell carcinoma and trichoepithelioma.
Poniecka AW, Alexis JB. Arkadi M. Rywlin M.D.
Department of Pathology & Laboratory Medicine, Mount Sinai Medical
Center, Miami, Florida, USA.
|
Am J Dermatopathol 1999 Aug;21(4):332-6 Abstract quote
The histologic distinction between tricheopithelioma and basal cell
carcinoma may be difficult in small biopsies. Immunohistochemical stains
have been used to help make this distinction; however, published studies
have generally been limited to a few antibodies.
To this end we performed a comprehensive immunohistochemical analysis
of 20 basal cell carcinomas and 10 tricheopitheliomas from our files,
in search of a consistent pattern of reactivity to distinguish the neoplasms
in biopsies. The antibodies used were: low molecular weight keratin
(Cam 5.2), Cytokeratin 7, (CK7), Cytokeratin 20, (CK20), Carcino-embryonic
antigen (CEA), CD30 (Ki-1), bcl-2, Ham 56, HPCA-I (CD34), and Ulex Europaeus
type I.
In our study, bcl-2 stained all but one basal cell carcinoma in a
diffuse pattern, whereas all tricheopitheliomas showed staining of the
outermost epithelial layer. No other stain proved to be an independent
marker for either neoplasm and no consistent immunohistochemical profile
for either neoplasm emerged.
Thus, we conclude that bcl-2 may be of some value in distinguishing
basal cell carcinoma from tricheopithelioma, limited by the quantitative
nature of the difference in staining. Histologic criteria applied to
H&E-stained sections remain the cornerstone of histologic diagnosis.
|
| p16 |
|
-
p16 expression in conventional and desmoplastic trichilemmomas.
-
Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35294-0009, USA.
|
-
The expression of p16 in cutaneous neoplasms is upregulated in melanocytic neoplasms, ultraviolet radiation-induced neoplasms, such as actinic keratoses and squamous cell carcinomas, and in lesions related to human papillomavirus, such as Bowen's disease and bowenoid papulosis. In cervical dysplasia and tonsillar carcinoma, there is such a close relationship between p16 and human papillomavirus (HPV) to the extent that p16 immunostaining is used as a surrogate marker for the presence of HPV proteins.
-
- In this study we were interested in the expression pattern of p16 in trichilemmomas. Twenty-six conventional and 19 desmoplastic trichilemmomas were immunohistochemically stained for p16. p16 immunostaining was noted in the majority of conventional (80.8%) and desmoplastic trichilemmomas (73.7%). The staining pattern was both nuclear and cytoplasmic. The staining intensity was more pronounced in the desmoplastic variant.
-
- We describe for the first time p16 expression in trichilemmomas and discuss our findings in conjunction with p16 expression found in other cutaneous neoplasms. Additionally, the relationship of p16 to HPV infection is critically evaluated.
|
| p27 |
|
|
Expression of p27kip1 in Basal Cell Carcinomas and Trichoepitheliomas.
Cesinaro AM, Migaldi M, Corrado S, Maiorana A.
Section of Pathological Anatomy, Department of Morphologic and Forensic
Sciences, University of Modena and Reggio-Emilia, Modena, Italy.
|
Am J Dermatopathol 2002 Aug;24(4):313-8 Abstract quote
Immunohistochemical analysis was used to evaluate p27kip1 expression
in normal hair follicles and in a series of 39 basal cell carcinomas
(BCC) (13 of superficial type, 7 infiltrating, 7 morphea-like, 12 nodular)
and 20 trichoepitheliomas (TE) (9 of classic type, 9 immature, 2 desmoplastic).
The labeling index (LI) was derived semiautomatically by means of a
computer-assisted cellular image analyzer, and statistical analysis
was carried out using the Student t test. A positive reaction for p27kip1
was detected in the hair germ papillae, in supramatrical cells, and
in the inner pilar sheath, whereas matrical cells and the outer pilar
sheath were negative. All BCC and TE cases showed a positive immunoreaction
for p27kip1, but the staining pattern was different in the two groups
of lesions, being patchy with focal peripheral accentuation in TE and
more diffusely dispersed in BCC. The quantitative study showed lower
p27kip1 expression in BCC (LI = 27.51 +/- 12.55) than in TE (LI = 45.27
+/- 20.27) (P < 0.0001). Statistically significant differences were
also observed between TE subgroups and nodular or infiltrating BCC subtypes.
The occurrence of a wide overlap of LI values hampers the practical
application of a p27kip1 LI in the differential diagnosis between BCC
and TE in difficult cases, however.
|
| Electron microscopy (EM) |
|
|
Merkel cells are integral constituents of desmoplastic
trichoepithelioma: an immunohistochemical and electron microscopic study.
Hartschuh W, Schulz T. Department of Dermatology,
University of Heidelberg, Germany.
|
J Cutan Pathol 1995 Oct;22(5):413-21 Abstract quote
The incidence of Merkel cells has previously been investigated in a
number of inflammatory and tumorous lesions of the skin. Special attention
was given to tumors with follicular differentiation.
In the present study we examined the localization of Merkel cells in
another adnexal tumor, the desmoplastic trichoepithelioma (n = 15),
as well as in its main differential diagnosis, the morpheiform basal-cell
carcinoma (n = 30). Using immunohistochemical methods, we found Merkel
cells as a stable constituent in desmoplastic trichoepitheliomas, but
failed to detect them in morpheiform basal-cell carcinomas. These findings
might therefore be an important tool in the sometimes very difficult
but clinically imperative distinction between these two conditions.
Furthermore, our study may be of interest in the discussion about the
origin of desmoplastic trichoepitheliomas. High numbers of Merkel cells
in desmoplastic trichoepitheliomas indicate a bulge-derived origin of
this adnexal tumor, since high numbers of Merkel cells, especially in
the bulge, were recently discovered.
Although the significance of Merkel cell hyperplasia in desmoplastic
trichoepithelioma is not presently understood, a regulatory role of
the Merkel cell in growth and development of this adnexal tumor is suggested.
|
| DIFFERENTIAL DIAGNOSIS |
KEY DIFFERENTIATING FEATURES |
| BASAL CELL CARCINOMA |
|
Does the panel of cytokeratin 20 and androgen receptor antibodies differentiate desmoplastic trichoepithelioma from morpheaform/
infiltrative basal cell carcinoma?
-
1Department of Pathology, 2Division of Biostatistics, Department of Medicine and 3Department of Pathology and Dermatology, Indiana University School of Medicine, Indianapolis, IN, USA
Katona TM, Perkins SM, Billings SD.
|
J Cutan Pathol 2008;35:174-179 Abstract quote
Background: Evaluation of androgen receptor (AR) and cytokeratin 20 (CK20) expression can aid in distinguishing between conventional basal cell carcinoma (characteristically AR+, CK20−) and trichoepithelioma (frequently AR−, CK20+). Within these two groups of tumors, morpheaform/infiltrative basal cell carcinoma (mBCC) and desmoplastic trichoepithelioma (DTE) are particularly challenging to differentiate both clinically and histologically. We investigated whether AR and CK20 immunostains may distinguish between mBCC and DTE.
Methods: Immunohistochemistry for AR and CK20 was performed on 15 DTEs and 31 mBCCs. Any immunoreactivity within the tumor for AR or CK20 was considered positive.
Results: AR expression was seen in 13% (2/15) of DTE and 65% (20/31) of mBCC cases (chi-square p = 0.0011). CK20-positive Mërkel cells were identified in 100% (15/15) of DTE and 3% (1/31) of mBCC (chi-square p < 0.0001). The expected pattern of AR−, CK20+ immunophenotype was present in 87% (13/15) of DTE cases. In mBCC, 61% (19/31) was AR+, CK20−. No DTE was AR+, CK20− and no mBCC was AR−, CK20+.
Conclusions: Immunohistochemical stains for AR and CK20 are useful to differentiate DTE from mBCC. The AR−, CK20+ immunophenotype is sensitive (87%) and specific for DTE (100%). The AR+, CK20− immunophenotype is specific (100%) and moderately sensitive (61%) for mBCC.
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Proliferative characterization of basal-cell carcinoma and trichoepithelioma in small biopsy specimens.
Lum CA, Binder SW.
Division of Surgical Pathology, LAC-USC Medical Center, USC-Keck School of Medicine, Los Angeles, CA, USA.
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| J Cutan Pathol. 2004 Sep;31(8):550-4. Abstract quote |
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We examined the proliferative characteristics of 20 basal-cell carcinomas (BCCs) and 16 trichoepitheliomas (TEps) in an effort to understand and explore possible differences in their tumorigenic cell-cycle properties. These tumors were first compared for their expression of the nuclear proliferative protein Ki-67 and the tumor suppressor protein p53. We also compared the p53 downstream effector, p21(waf-1/cip-1), an inhibitor of cyclin-dependent kinases. The other p53-dependent, cyclin-dependent kinase inhibitor, p27(kip-1), has shown to be increased in TEps, which is consistent with this benign neoplasm's better-differentiated state.
In our findings, we confirmed through immunohistochemical staining for Ki-67 that BCCs qualitatively showed a greater proliferative fraction compared to TEps (50.0 vs. 13.0%, p < 0.00001) as well as over-expression of p53 (2+ vs. 1+, p < 0.0008). BCCs marked by p21 demonstrated scattered nuclear positivity compared to the virtual absence of staining in the TEps (p < 0.019). In studying their cell-cycle properties, our findings suggest that abnormalities in the p53 pathway allow BCCs to obtain a growth advantage.
We show that Ki-67 and p53 staining both appear useful in resolving challenging differential diagnoses and thereby help in directing appropriate treatment strategies.
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Criteria for histologic differentiation of desmoplastic trichoepithelioma
(sclerosing epithelial hamartoma) from morphea-like basal-cell carcinoma.
Takei Y, Fukushiro S, Ackerman AB.
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Am J Dermatopathol 1985 Jun;7(3):207-21 Abstract quote
Histological differentiation between desmoplastic trichoepithelioma
and morphea-like basal-cell carcinoma may be exceedingly difficult.
Because the criteria for this differentiation published to date have
not proved satisfactory to us, we undertook a study with the aim of
formulating repeatable and reliable criteria for distinguishing between
these two conditions of wholly different biological potential.
We believe that the 26 sets of criteria listed here will permit reliable
differentiation of desmoplastic trichoepitheliomas from morphea-like
basal-cell carcinomas, even in biopsy specimens taken by shave and punch
techniques. |
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Trichoepithelioma: a 19-year clinicopathologic re-evaluation.
Bettencourt MS, Prieto VG, Shea CR.
Department of Medicine, Duke University Medical Center, Durham,
North Carolina, USA. |
J Cutan Pathol 1999 Sep;26(8):398-404 Abstract quote
Accurate histopathologic distinction between trichoepithelioma (TE)
and basal cell carcinoma (BCC) may be challenging.
From 97 cases diagnosed as TE during the period 1979-1997, 73 available
cases were studied with regard to: 1) stroma; 2) retraction effect;
3) papillary-mesenchymal bodies (PMB); 4) amyloid; 5) mitotic figures;
6) apoptotic cells; 7) inflammation; 8) granuloma; and 9) calcification.
A judgment was made regarding diagnosis. The patients' medical records
were subsequently reviewed for clinical features and possible recurrence.
The diagnosis of TE was confirmed histologically in 48 (65%) of 73 cases.
Fifteen cases (21%) were reclassified as BCC (RC-BCC), eight other cases
(11%) were reclassified as other lesions, and two additional cases (3%)
could not be confidently classified as either TE or BCC.
The most helpful differentiating features were the presence of retraction
effect (in 100% of RC-BCC vs. 37% of TE), myxoid stroma (in 80% of RC-BCC
vs. 12% of TE) and PMB (in 20% of RC-BCC vs. 81% of TE). Unexpected
findings in TE were detection of amyloid in 33%, apoptotic cells in
100%, and mitotic figures in 46%.
Five of the 15 RC-BCC have recurred (33%), whereas there have been
no recurrences in the confirmed TE group.
A constellation of histopathologic criteria may help to discriminate
problematic examples of trichoepithelioma from basal cell carcinoma. |
