Localized epidermotropic reticulosis (Woringer-Kolopp disease).

In order to clarify the biologic behavior and establish clinical and histologic criteria for the diagnosis of a cutaneous disease originally described by Woringer and Kolopp, we examined fifteen new cases and reviewed thirteen reports. The disease presents as a single, chronic, asymptomatic, circinated, scaly plaque. It preferably involves distal extremities and affects middle-aged individuals, as well as a considerable number of youths. The male to female ratio is 2:1. The treatment of choice is surgical excision or radiotherapy. One lesion resolved with an intralesionally administered steroid. Follow-up data of the twenty-eight cases suggest that this is a benign lesion. Paradoxically, its atypical microscopic features contrast with its benign clinical appearance and biologic behavior. The lower epidermis appears focally infiltrated by large atypical mononuclear cells that spare the dermis. Ultrastructural observations suggest that these are stimulated T lymphocytes, which sometimes are mixed with histiocytes. We propose the term "localized epidermotropic reticulosis" for this distinct clinicopathologic entity, which is different from mycosis fungoides.