Malignant clear cell hidradenoma of the upper lip.

Malignant clear cell hidradenoma is an uncommon tumor of eccrine sweat gland origin that has a predilection for the head and neck. It is characterized by an indolent growth pattern yet frequently recurs following surgical excision and has a high incidence of regional and distant metastases. A case of recurrent malignant clear cell hidradenoma of the upper lip is presented. The lesion was treated with surgical excision followed by radiotherapy. The literature on this rare lesion is reviewed and treatment strategies discussed.