Case Number : Case 2376 - 2 August 2019 Posted By: Dr. Richard Carr

The tumor in lower dermis-subcutis appears to be hidradenoma, not sure of the superficial islands and lobules in image 3 - but could be dermal duct tumor. The composite tumors with a combined silhouette of both hidradenoma and dermal duct tumor displaying either poroid or apocrine differentiation can occur. 

BCC overlying a hidradenoma...diff with an odd bcc with apocrine and ductal differentiation.

BER EP4 positive diffuse and EMA negative suggests BCC may be over a poroid tumor

Interesting. BCC overlying hidradenoma 

I dont know why there is diffuse positive of Ber EP4 in poroid component

porocarcinoma may show diffuse positive but poromas should show focal positivity

BerEP4 is widely expressed in tumors of the sweat apparatus: a source of potential diagnostic error.

Thanks. This is a BCC. BCC can very closely mimic hidradenoma. The signature of diffuse strong BerEP4 highlighting the peripheral palisade and completely negative EMA in the basaloid cells is practically pathognomic of a BCC. You must always run EMA in combination with BerEP4 (which I fear, from memory, the Afshar paper did not do and therefore one could question their findings). Most of the apparent ductal / glandular differentiation here is pseudo (stromal, note the small blood vessels in the spaces in some areas). There is a duct-like space centrally but remember BCC can show ductal differentiation. Remember calcification is rather typical of follicular neoplasms. I have made the error of reporting hidradenoma as BCC and vice versa in the past till I paid attention to these details. Also I've noted in this sub-type of BCC one can find the BerEP4 only strong in the peripheral basaloid areas and may be markedly reduced in the more squamoid component. Make sure your BerEP4 has strong internal controls.

Thanks Richard. Good learning points.

Thanks sir, very useful points