Case Number : Case 1438- 28 December Posted By: Guest

The silhouette looks like a keratoacanthoma with basaloid and sebaceous differentiation. Atypical site for a sebaceoma, my first diagnosis, and some beyond border atypia. So i'm thinking to a "low grade sebaceous carcinoma developed in sebaceoma"

Sebaceous carcinoma.

Sebaceoma

I would suggest a sebaceoma with atypical features and I would state the exact mitotic activity. As the tumor is superficial, has pushing borders, is smaller tan 1 cm. and the surgical margins are free it would be important also to state that metastatic potential is around 0% on the report

Sebaceous carcinoma

I figured that there would be disagreement on this one.  Here is my diagnosis:

-- SEBACEOUS CARCINOMA, MODERATELY DIFFERENTIATED

COMMENT:  I do believe there is a loss of PMS2 in this lesion.  There is some diminution of MLH-1, but some areas of it seem to be positive.  Consideration for the possibility of the Muir-Torre syndrome should be entertained on this basis.

This lesion from the left upper arm consists of a sebaceous gland neoplasm characterized by asymmetry and some degree of internal heterogeneity.  There is a fairly prominent germinative component to the lesion with a minor degree of terminal differentiation in lobules.  These basophilic germinative cells have some degree of nuclear pleomorphism with mitotic figures found relatively easily and with some nuclear overlapping.  Immunohistochemically, this lesion is negative with PMS-2 and mostly negative with MLH-1, although there are arguably areas within it of positivity.  There is no loss of MSH-2 or MSH-6 in the lesion.