Case Number : Case 2042 - 04 April 2018 Posted By: Dr. Richard Carr

Islands of basaloid cells with sebaceous differentiation and ductal structures- sebaceoma.

Agree with Anil. Sebaceous carcinoma.

its ulcerated and shows asymmetry and mitosis. Sebaceous carcinoma.  Any loss of MMR / family history suggestive of MTS?

Agree with sebaceous carcinoma. 

I'm concerned about sebaceous carcinoma too. There are certainly sebaceous units in the external auditory canal. It's  an unusual location for this tumor, and makes one think even more of Muir-Torre. 

Favor well diff seb carc

Sebaceous carcinoma but I think super rare location. Doesn't look like bcc  with seb differation to me.

The architecture appears to favor a sebaceoma in terms of not being infiltrative. However cellular crowding and atypia suggest malignancy. This combination of findings are suggestive of a well-differentiated Sebaceous carcinoma in the setting of MTS.

Diagnosis: Sebaceous, rather mitotic!

H&Ex6; IHCx4 at 6pm

On behalf of Dr Richard Carr.

Okay I called this an "atypical" sebaceoma and recommended complete excision. Good discussion. Lesion appeared to have pushing only borders. I was impressed by the nice abrupt transition from germinative to mature sebocytes typical for sebaceoma but like you all was concerned by the high mitotic rate. The IHC pattern for BerEP4 and EMA was similar to that we saw in sebaceomas (published a few years back in Histopathology). I think mentioning Muir Torre is also mandatory even if you say it in a way that might indicate a low risk. e.g. Solitary lesions on the head in older patients have a low prediction for Muir Torre but please consider the possibility.  I have not follow-up as yet.