Case Number : Case 836 - 30th August Posted By: Guest

My differential diagnosis would be :
Fibroepithelioma of Pinkus
Tumor of the follicular infudibulum
Trichoepithelioma
clinically Fibroepithelioma of pinkus fits more ,
the connection to the epidermis would exlude trichoepithelioma
the proliferation of basalod cell and not keratinocytes would favor a diagnosis of Pinkus which the pt could have for years, any way this is a punch biopsy and complete excision would be more helpful with immunos.

acrosyringial nevus vs syringocyctadenoma papilliferum vs fibroepithelioma of pinkus but i favour the first two because of the presence of ducts

FEP which is already a trichoblastoma

Syringofibroadenoma (acrosyringeal nevus)

Agree, favor Pinkus FE due to pronounced reticulated pattern plus fibromucinous surrounding stroma. Small cysts filled with keratin and lacking granular cell layer might suggest infundibulocystic BCC at an odd site.

add chondroid syringioma (Mixed tumor of skin).

I found this lesion hard to classify, but I think three diagnosis are possible, all of them characterized by anastomosing epithelial strands connected to the undersurface of the epidermis.

[url="http://journals.lww.com/amjdermatopathology/Abstract/1994/12000/Fibroepithelioma_of_Pinkus__Eccrine_Duct_Spread_of.2.aspx"]Fibroepithelioma of Pinkus with eccrine duct spreading[/url].
Supportive findings: basaloid cells; peripheral palisading.
Adverse findings: lesion is not typically located on the trunk; there’s no persuasive specific follicular stroma; follicular papillae are lacking.

[url="http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3120003/pdf/ad-23-70.pdf"]Syringofibroadenoma[/url].
Supportive findings: fibrovascular mucinous stroma with lymphocytic infiltrate; ductal elements within strands; areas of squamous cells.
Adverse findings: peripheral palisading.

[url="http://journals.lww.com/amjdermatopathology/pages/articleviewer.aspx?year=2009&issue=10000&article=00002&type=abstract"]Tumor of the follicular infundibulum with ductal differentiation[/url].
Supportive findings: peripheral palisading.
Adverse findings: lesion is not typically located on the face; cells have scant rather than abundant pale eosinophilic cytoplasm; strands are not parallel to the skin surface.

BCC, FEP-type
The basaloid neoplasm focally involves a normal eccrine duct , has cytologic atypia, peripheral palisading, mucinous stroma and infundibulocystic squamous metaplasia.

Fenestrated trichoblastoma (fibroepithrlioma of Pinkus).

Favor Fibroepithelioma of Pinkus with eccrine duct spreading.

I reported this as a fibroepithelioma-(Pinkus-)like BCC. The lesion lacks the stromal condensations of papillary mesenchymal cells and longer fenestrations of a bona fide Pinkus tumour. Immunos were helpful as the lesion lacked reactive Merkel cells and CD10 stromal cells that are always seen in Pinkus tumour (a fenestrated trichoblastoma). I would therefore agree with the designation of infundibulocystic BCC, Pinkus-like.