Mycosis fungoides and eruptive epidermoid cysts: a unique response of follicular and eccrine structures

A case of a patient who developed simultaneously mycosis fungoides (MF) and multiple, tiny eruptive cutaneous cysts on the face, neck and upper part of the trunk is reported. Histologically and immunohistochemically MF infiltrate was recognized not only in the upper part of the dermis and in the epidermis but also around and within the walls of cystic lesions. Furthermore, the eccrine structures were also involved by MF infiltrate. We emphasize that MF infiltrate can affect the follicular and eccrine structures inducing the formation of keratinous cysts. The clinical appearance of the facial lesions may be confused with Favre-Racouchot disease.