Primary cutaneous cribriform carcinoma

I'd first like to rule out metastatic colorectal carcinoma because of the dirty necrosis and focally palisading glands. If cdx2, CK20 and history are negative then consider adnexal carcinoma with sweat gland differentiation, such as cribriform carcinoma. Sweat gland carcinomas are usually CK5/6 and p63 positive, and p63 highlights myoepithelial layers.  

Metastasis adenocarcinoma. Primary may be in the colon, rectum, prostate or thyroid. In addition to CK 5/6 and p63, PSA ,thyroglobulin, TTF1 stains needed.

Metastatic adenocarcinoma ( lung? ).  CK7 CK20 TTF1 CDX2 could be useful. 

Thank you all for the great comments. Yes following immuno' and careful analysis the final diagnosis is:  Lymphoepithelioma-like carcinoma

Dr Iskander Chaudhry

Sorry, there was a slight confusion- I think Iskander meant to post his answer to the next case!

This gentleman did indeed have gastric carcinoma, and this is a metastatic deposit. Kudos to those who recommended a metastatic work up! CK7, CK20, and CDX2 were all positive. TTF1 was negative.