Unusual presentation of primary orbital microcystic adnexal carcinoma.

Microcystic adnexal carcinoma (MAC) is a rare and locally aggressive malignancy that occurs on the face, can invade deep tissue, and can rarely invade the orbit via perineural spread. It has been reported most often in the form of a cutaneous lesion. Although there have been 3 prior case reports of an orbital presentation of MAC, all have been from undiagnosed cutaneous or subcutaneous lesions. We report a rare case of a primary orbital MAC in a 39-year-old healthy woman who presented with progressive diplopia and enophthalmos without evidence of any cutaneous or subcutaneous lesions.