Answer of Dermatopathology Case 22

Fibroepithelioma of Pinkus

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Abstract:

Variations in clinical presentation of basal cell carcinoma. Acta Clin Croat. 2008 Mar;47(1):25-30.

Basal cell carcinoma (basalioma, BCC) is the most common skin cancer and the mostcommon human malignancy in general, with a continuously increasing incidence. In most cases, BCC develops on chronically sun-exposed skin in elderly people, most commonly in the head and neck region. Besides chronic UV radiation, other risk factors for the development of BCC include sun bed use, family history of skin cancer, skin type 1 and 2, a tendency to freckle in childhood, immunosuppression, previous radiotherapy, and chronic exposure to certain toxic substances such as inorganic arsenic. There are numerous variations in clinical presentation of BCC, such as nodular BCC, ulcerating BCC, pigmented BCC, sclerosing BCC, superficialBCC, and fibroepithelioma of Pinkus. Each varies in terms of clinicalpresentation, histopathology and aggressive behavior. Treatment modalities for BCC include surgical excision, cryosurgery, curettage, electrodessication, radiotherapy, photodynamic therapy, topical cytostatics, and immunomodulators. If left untreated or inadequately treated, BCC may become invasive and locally destructive, although it very rarely metastasizes. Due to the extremely high incidence of BCC, medical professionals should be familiar with its manifold clinical presentations.

Fibroepithelioma of pinkus in a 9-year-old boy: a case report. Cases J. 2008 Jun 27;1(1):21.

ABSTRACT: Fibroepithelioma of Pinkus (FEP) is a rare indolent variety of basalcell carcinoma that is typically polypoid and located on the trunk of adult malesaged 40-60 years. Basal cell carcinoma (including FEP) is very rare in the pediatric population. We are reporting such a case occurring in a 9-year-old boy.

Fibroepithelioma of Pinkus with pleomorphic epithelial giant cells. Dermatol Online J. 2008 Dec 15;14(12):13.

Fibroepithelioma of Pinkus is a rare, indolent variant of basal cell carcinoma(BCC). The presence of pleomorphic giant cells in such a tumor is extremely rare and to our knowledge, only one such case has been previously reported in theliterature. We report another case occurring as a pedunculated, gluteal lesion in an 82-year-old man. The nodule was lightly pigmented, polypoid, and measured 1.0 cm in greatest dimension. Immunohistochemical staining confirmed that the giant cells were of epithelial origin and that the proliferative rate of these cells was low.

Expression of androgen receptor by fibroepithelioma of Pinkus: evidence supporting classification as a basal cell carcinoma variant? Am J Dermatopathol. 2007 Feb;29(1):7-12.

The classification of fibroepithelioma of Pinkus as basal cell carcinoma or trichoblastoma remains controversial. Immunohistochemical stains for androgenreceptor may be useful in differentiating basal cell carcinoma fromtrichoepithelioma or trichoblastoma. We studied androgen receptor expression in13 fibroepitheliomas of Pinkus, 11 basal cell carcinomas, 12 trichoepitheliomas, and 3 trichoblastomas. Androgen receptor expression was present in 77% (10/13) of fibroepitheliomas of Pinkus, 73% (8/11) of basal cell carcinomas, 17% (2/12) of trichoepitheliomas, and 0% (0/3) of trichoblastomas. Androgen receptor expressionwas significantly higher in fibroepitheliomas of Pinkus compared withtrichoepitheliomas and trichoblastomas (P = .0007), but not basal cell carcinoma (P = 1.00). Tumor-associated Merkel cells, a feature of benign follicular tumors,was identified by cytokeratin 20 stains. Merkel cells were identified in 85%(11/13) of fibroepitheliomas of Pinkus, 27% (3/11) of basal cell carcinoma cases, and 73% (11/15) of benign follicular tumors. Cytokeratin 20 expression was significantly higher in fibroepithelioma of Pinkus and benign follicular tumorscompared with basal cell carcinomas (P = 0.0111 and P = 0.025, respectively). No significant difference was found between fibroepitheliomas of Pinkus and trichoepitheliomas and trichoblastomas (P = 1.00). Similar to basal cellcarcinomas, fibroepitheliomas of Pinkus express androgen receptors, potentially supporting classification as a basal cell carcinoma. Conversely, fibroepitheliomaof Pinkus demonstrates retention of Merkel cells, a feature of benign follicular tumors. Immunophenotypic evidence for the classification of fibroepithelioma of Pinkus remains inconclusive. In small, partial biopsy specimens, coexpression of androgen receptor and cytokeratin 20 may aid in the diagnosis of fibroepithelioma of Pinkus.

Fibroepithelioma of pinkus is a fenestrated trichoblastoma. Am J Dermatopathol. 2005 Apr;27(2):149-54.

Pinkus described "pre-malignant fibroepithelioma" as a proliferation that gave rise to many tiny basal cell carcinomas within each lesion. Later authors have generally considered it to be an unusual variant of basal cell carcinoma (BCC).The delineation of trichoblastoma as the general term for the benign counterpart of BCC raises the possibility that the fibroepithelioma of Pinkus (FEP) would be better classified under that rubric. To address this subject, we examined the records of 114 patients with FEP for body site, age and sex distribution, and sections from 75 lesions. All FEP examined show a blunt interface with the underlying dermis (where one could be seen), differentiation toward follicular bulbs and papillae, and large areas of cellular stroma. FEP has a slight female preponderance in contrast to BCC, which is more common in males. Unlike the common types of BCC, FEP has an overwhelming predilection for the trunk and extremities, and only 5% of tumors are set in a dermis with significant amounts of solar elastosis. Next, FEP, BCC, and FEP with BCC-like areas were stained with MIB-1 (to assess proliferation), p53 (an oncogene product), and CK20 (a Merkel cell marker) antisera. FEP shows a low level of staining for p53 and MIB-1, in contrast to conventional BCCs that over-express these markers. FEP also shows retention of Merkel cells, a characteristic of benign neoplasms with follicular germinative differentiation but not in general of BCC. The BCC-like areas in some FEP tumors reflect these staining tendencies with less striking differences. Given the contrast between FEP and BCC with respect to site of occurrence, relationship to sun damage, histopathologic features, and immunohistochemical studies, it appears that FEP more closely resembles trichoblastoma than BCC.