Case Number : Case 2193 - 5 November 2018 Posted By: Limin Yu

Sarcomatoid carcinoma plus porocarcinoma in situ

Porocarcinoma in situ.

I have to recognize that I didn't see the sarcomatoid component. But agree with Amer. 

Porocarconima in situ and invasion

Agree with porocarcinoma, with a widely in situ growth, and a dedifferentiated invasive component.

What are the criteria for porocarcinoma in situ?

Poroma proliferates in the dermis and form nodules of poroid cells. So just because there are nodules of poroid cells in the dermis , it does not mean it is invasive. So when is a tumor invasive? I remember Dr. Ackerman said that the silhouette of the tumor is very important to render the diagnosis of porocarcinoma. Is the silhouette of this tumor justified it as invasive?

I do not see cytologic atypia. Necrosis does not count because necrosis en masse is actually a typical feature of  poroma. I think it is a very a difficult case and would be a little bit conservative before calling this right out porocarcinoma.

very interesting remarks! Indeed not easy to decide if its invasive or not @anh

After all these years working with the microscope i learned there aren’t abosolute criteria to decide about the malignancy and infiltration of a tumor. The General pathology is a beautiful and useful scientific reference point... but it’s an abstraction. As a hands-on pathologist I made an invasive Porocarcinoma diagnosis following these criteria: 1) this a cancer because of cytoarchitctural atypia. 2) this is a poroid cancer because of ductal eccrine differentiation. 3) there are dedifferentiared invasive ( desmoplasia and epithelial strands) components in fig 1 2 7 8 13.   But this is a subjective assessment of course. 

Agree in favouring a porocarcinoma in situ and a presumed invasive more spindle pattern (not shown at high power). I'd be interested in the pattern of Ki67, p16 & p53 in the lesion. It looks rather basaloid / neuroendocrine (although may just be the thick sections photographed). I'd run CD56, synaptophysin, neurofilament, chromogranin for interest.  We're doing this in basaloid bowen's and picking up some cases with NED that I suspect are independent of Merkel (virus).