Case Number : Case 1962 - 6 Dec 2017 Posted By: Dr. Richard Carr

Squamoid eccrine ductal carcinoma-SEDC

Interesting ... I would consider a MAC - site not given and would take into consideration

MAC

It's from the cheek.

I thought this was a fairly typical case of microcystic adnexal carcinoma. I tend to regard low grade squamoid eccrine ductal and syringoid (+/- sclerosing) sweat gland carcinomas as a group with similar implications i.e. locally infiltrative but without significant metastatic potential. This is provided they are cytologically only relatively mildly atypical and with low mitotic activity (e.g. <1/mm2 or 1 or 2 per 10 hpf). Obviously Moh's or other margin control surgery may be required because despite their rather indolent features they may have grown quite extensively over many years and be difficult to extirpate especially when there is growth along the nerves.  Fortutantely this was a relatively small lesion that lacked perineural spread. I must emphasise the diagnosis can be perilous on small and superficial biopsies.

Hi Richard, I agree with your interpretation but was under the impression that MACs were usually very bland. This has fairly distinctive cytologic atypia.

Agree this case does have atypia (I thought mild) and also some mitotic figures but I'd still put in the "neglible" risk for metastasis group.  Eduardo Calonje's group presented a series in Delhi, they labelled squamoid eccrine ductal carcinoma that included cases with quite marked atypia I suppose you might consider this case on the lower grade end of that spectrum.  Personally for higher grade lesions I prefer to label as "adenosquamous carcinoma" rather than use SEDC that originally were described as "low grade" lesions.