Case Number : Case 2355 - 27 June 2019 Posted By: Uma Sundram

Sebaceous carcinoma in situ. 

Or merkel cell ca in situ, depending on what the stains are. In Fig6 the intraepidermal cells show paranuclear dot like positivity.

Nice challenge case. In my opinion the pattern of the IHC is more in keeping with a CK20 so i favor Merkel Cell Carcinoma.

I believe this is in situ sebaceous carcinoma. Picture 1 show some bubble cytoplasm and 2 of the 3 markers should be EMA and Adipophilin. Merkel in situ is so rare and the localizaton also favors sebaceous carcinoma. But I liked this possibility, nice hypothesis!

zeis type sebaceous gland carcinoma-adipophilin needed

However it presents as recurrent blepharo conjunctivitis and occurring on cheek I am concerned

May be other tumors with intraepithelial spread like Melanoma/ Bowens/

Merkel I am aware of epidermotropic but not sure of intraepithelial

I just read yes pagetoid spread of Merkel cell carcinoma is one of differential diagnosis along with metastatic small cell carcinoma with intraepithelial spread

lets wait for IHC

Agree with sebaceous carcinoma in situ. 

Hi everyone! It took me some time to find my posted case but I think we are now back on track. I thought I had included the stain identifications in my text, but it didn't make it to the posted history. My apologies for that! Anyway, image 4=ck7, image 5=ema, image 6=cam5.2. As you can see, all three are positive. However, ck20, adipophilin, and androgen receptor are all negative. It's nice to get this feedback from the audience, because I felt silly not immediately thinking of SCCIS in this case. But, I think cases like these are challenging, and the worst is to miss a subtle sebaceous carcinoma in a periocular location.

Diagnosis= SCCIS or Bowen's disease. 

Highly fascinating case that looks like basaloid bowen's/BAK (I don't use SCCIS term) on initial look but has Cam5.2 (LMWCK) with dot positivity. Needs CK20, CD56, synaptopysin, chromogranin, Neurofilament, BAK/Bowen's does not usually stain for LMWCK and never with dot-positivity in my limited experience (I rarely run Cam5.2 on Bowen's). It may be a combined lesion (Bowen's and MCCis) or a bowen's showing divergent neuroendocrine differentiation. Would be nice to run the IHC for MCPyV.

We've collected a series of "non-Merkel" bowen's / SCC invasive with areas of neuroendocrine differentiation (they did not show usually show dot positivity with Cam5.2/CK20 but were positive for 2 or more NED markers).

I'd also add p16, p53, p63, BerEP4, EMA