Sclerosing sweat duct carcinoma of the orbit.

Sclerosing sweat duct carcinoma or microcystic adnexal carcinoma is a rare, aggressive and locally destructive sweat gland malignancy. It is difficult to diagnose clinically and histologically and as such is probably under-recognized. Late recognition is common and is associated with extensive tissue loss. Local extension into the orbit from periorbital cutaneous lesions is documented, necessitating exenteration for adequate tumor clearance. We report a case of orbital sclerosing sweat duct carcinoma without a clinically evident cutaneous lesion, which required exenteration in a patient with no identifiable risk factors. Inclusion of sclerosing sweat duct carcinoma in the clinical and histological differential diagnosis of orbital masses and reporting of cases will lead to increased recognition of this malignancy, add to our understanding of its natural history and improve patient outcomes.