Case Number : Case 1847 - 27 June - Dr Uma Sundram Posted By: Guest

Dr Uma Sundram wraps up her June cases with a lovely set of images.

Geoff Cross - DermpathPRO Projects

Follicular induction overlying Dermatofibroma.

I thought of superficial trichoblastoma and wonder about an association with nevus sebaceous, if clinically consistent.

Why not a BCC overlying a DF? There is peritumoral mucinous retraction artefacts. 

Islands of basaloid cells, palisading and retraction artefact- suggestive of BCC

I do not discard bcc only with morphology in this case. Although, based only on the H and E, the stroma looks quite cellular for me and the morphology more consistent with a tumor of trichoblastic origin

There is indeed a basal cell carcinoma for the reasons set out above by Mona. I am not convinced that stromal hypercellularity truly represents a dermatofibroma. Maybe the proliferation of small vessels in the fibrotic superficial dermis indicates stasis dermatitis, a condition that can be complicated by such tumor.

I also thought of superficial BCC, but, after Dermpath1,s comment, looked more closely the dermal component, and now agree with an exorbitant basaloid induction by a DF.

BCC

BCC or "BCC-like changes, basaloid hyperplasia" overlying a probable DF. Does any colleague has experience with usefulness of CK20 in differentiating between the two? Sebaceous structures at the edge of lesion is also interesting. It emphasise protean changes that can be encountered over a DF, making them concerning or confusing at least clinically &/or dermoscopically. 

Great DDX and the reason I posted this difficult case. We finally went with BCC overlying a DF. The basaloid cells express Ber Ep4 and lack staining with CK20 (absent Merkel cells). Factor XIIIa highlights the dermal fibroblasts. I was quite swayed by retraction artifact and central necrosis, which are not features I associate with trichoblastoma or follicular induction. There was no surrounding nevus sebaceus.