Subungual Epidermoid Inclusions-A Series of 8 Cases and a Review of Literature.

Subungual epidermoid inclusions (SEI) are benign cystic lesions of the nail bed. To our knowledge, there has been only one case series describing SEI. We report eight cases of SEI. The patients had a median age of 72 years (range 3-84) with a female: male ratio of 1.6. Five occurred in toenails and three in fingernails. Histologically, SEI is characterized by bulbous proliferation of rete ridges and unilocular cysts lined by thin squamous epithelium with hypogranulosis, filled with orthokeratin. The connection to the nail bed epithelium may be disrupted and calcified. SEI are tumors that should be kept in the differential diagnosis of the subungual nail bed lesions.