What is Fibroepithelioma of Pinkus ? Is it just a rare variant of Basal Cell Carcinoma? Dr Sampurna Roy MD

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What is Fibroepithelioma of Pinkus ?

Is it just a rare variant of Basal Cell Carcinoma?

Dr Sampurna Roy MD

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What is Fibroepithelioma of Pinkus?

Is it just a rare variant of Basal Cell Carcinoma?

Dr Sampurna Roy MD

Fibroepithelioma of Pinkus (FEP) was described as premalignant fibroepithelial tumor of the skin by Herman Pinkus in 1953.

According to Pinkus "these tumors do not constitute a truly new entity, but rather, that they are unusual variety of basal cell epithelioma".

Although FEP is currently accepted as a variant of basal cell carcinoma (BCC), its classification still remains controversial.

According to some authors FEP represents a fenestrated trichoblastoma/ trichoepithelioma.

FEP shares features of both trichoblastoma and BCC.

"Derived from the same cell type BCC and trichoblastoma represent opposite ends of the spectrum of differentiation, with FEP deserving an intermediate classification."

Differential Diagnoses: BCC ; Trichoblastoma, and Trichoepithelioma.

- Androgen receptor is expressed both in BCC and FEP but minimally in trichoblastoma.

- Merkel cells are found both FEP and trichoblastoma but they are absent in BCC.

In small, partial biopsy specimens, coexpression of androgen receptor and cytokeratin 20 may aid in the diagnosis of fibroepithelioma of Pinkus.

How is fibroepithelioma of Pinkus (FEP) different from basal cell carcinoma (BCC)?

Fibroepithelioma of Pinkus

- Has a predilection for the trunk and extremities

- Only 5% of tumours are set in a dermis with significant amounts of solar elastosis.

- Shows a low level of staining for p53 and MIB1, in contrast to conventional BCCs that over-express these markers.

- Shows retention of Merkel cells, a characteristic of benign neoplasms with follicular germinative differentiation but not in general of BCC.

Basal Cell Carcinoma

Note:

Until the 1990's, BCC was viewed as the most common epithelial neoplasm developing in association with nevus sebaceous.

Currently, trichoblastoma is thought of as the most prevalent basaloid neoplasm in nevus sebaceous.

The follicular stem cell marker pleckstrin homology-like domain, family A, member 1 (PHLDA1) also known as T-cell death-associated gene 51 (TDAG51) labels trichoepitheloma but not BCC.

In FEP, PHLDA1 labels the anastomosing network of thin cellular strands but not the basaloid nubbins.

Immunoreactivity for PHLDA1 correlates positively with the presence of Merkel cells

Key microscopic features:

Two or three cell thick anastomosing strands of basaloid or squamous cells ending in small nubbins of peripherally palisaded cells.

Epithelial component surrounded by abundant fibroblast rich stroma.

Mitotic activity or significant cellular atypia, as well as sign of solar dermatosis are absent.

Variants: Giant ; Pleomorphic Pigmented ; Hidradenomatous and Cystic.

Treatment:

The definitive treatment for FEP is complete excision.

Other treatment options include electrodessication and curettage, cryosurgery, or Moh's micrographic surgery.

Source:

-Pinkus H. Premalignant fibroepithelial tumors of skin. AMA Arch Derm Syphilol. 1953;67(6):598–615.

- Calonje E, Brenn T, Lazar A, McKee P. 4th Ed. Amsterdam: Elsevier Ltd; 2012. McKee's Pathology of the Skin with Clinical Correlations.

- Bowen AR, LeBoit PE. Fibroepithelioma of Pinkus is a fenestrated trichoblastoma. Am J Dermatopathol. 2005;27(2):149–54.

-Ackerman AB, Gottlieb GJ. Fibroepithelial tumor of Pinkus is trichoblastic (basal-cell) carcinoma. Am J Dermatopathol. 2005;27(2):155–9.

- Basaloid tumors in nevus sebaceus revisited: the follicular stem cell marker PHLDA1 (TDAG51) indicates that most are basal cell carcinomas and not trichoblastomas. J Cutan Pathol. 2013 May;40(5):455-62. doi: 10.1111/cup.12107. Epub 2013 Mar 14

- Fibroepithelioma of Pinkus Revisited. Dermatol Ther (Heidelb). 2016 Jun 21

- Fibroepithelioma of Pinkus is a true basal cell carcinoma developing in association with a newly identified tumour-specific type of epidermal hyperplasia. Br J Dermatol. 2012 Jan;166(1):88-97. doi: 10.1111/j.1365-2133.2011.10612.x. Epub 2011 Nov 24.

-Marušić Z, Kos M, Labinac-Peteh L, Bečić MP, Vranić S, Luzar B. Cystic fibroepithelioma of Pinkus: two new cases and cystic changes in classical fibroepithelioma of Pinkus. Bosnian Journal of Basic Medical Sciences. 2014;14(4):205-208.