Case Number : Case 1695 - 25 November - Dr Richard A Carr Posted By: Guest

Richard has a great case for you today with 7, yes SEVEN, more images at 6pm GMT

Geoff Cross - DermpathPRO Projects

Squamoid eccrine ductal carcinoma.

Agree with squamoid eccrine ductal carcinoma.

I had the same impression as the colleagues. There are just some points where I have some doubts. First, In these pictures there is a central area where the epidermis has large keratinocytes with ample pale cytoplasm and these changes extend to the infundibulum. However at the periphery the cells are more crowded with a bit of atypia and mitotic activity. If these changes are real this could be also interpreted as an squamous cell carcinoma with ductal differentiation. Im aware that some authors consider SEDC as a variant of MAC and others as a variant of squamous cell carcinoma. Maybe it would be interesting to perform p53 and p16 among other markers as these are rarely affected in MAC or SEDC but commonly altered in SCC. 

Adenosquamous carcinoma is possible

Thought of squamoid eccrine ductal carcinoma. Waiting for the 7 yet to come images !!

Squamoid eccrine ductal carcinoma is my first thought, but it wouldn’t be a surprise if this lesion represents an extension from a bone metastasis of a breast ductal carcinoma.

This is a difficult case for me, because:

1) the overal silhouette looks like a MAC.

2) the structural and cytological details fit better instead on a high grade infiltrating carcinoma ( MAC is a low grade one ).

3) there is an unquestionable eccrine differentiation.

I was thinking of a Porocarcinoma, also of a eccrine ( syringoid ) carcinoma...but that's because I don't know enough SEDC. 

The pattern of superficial squamous proliferation and  deeper ductal proliferation is common to both squamoid eccrine ductal carcinoma and MAC. (which is why the former is considered by some to be a variant of the latter).The diffuse cytological atypia and mitoses support SEDC over MAC.

Agree that mets need to be excluded. 

Differential

Porocarcinoma with squamous differentiation

SEDC

MAC

More images added... hope they clarify matters...

Geoff Cross - DermpathPro Projects

For me personally I've kept squamoid eccrine ductal carcinoma for exceedingly low-grade lesions akin to MAC. In this case I think the lesion is more of an intermediate grade.  Some will call this porocarcinoma, some will call it squamoid eccrine ductal carcinoma and some will call it adenosquamous carcinoma (my preferred designation). I think the main thing will be to collect large series to see if there are any features that can be associated with metastatic potential. In general infiltrative carcinomas like this case to me are relatively low-risk for metastasis and we probably worry too much about the name. I don't suppose it's surprising to get cutaneous adenosquamous carcinomas of follicular-ductal origin.