[Unilesional plaque-type mycosis fungoides: 3 cases]

The clinical course of unilesional plaques with a histological diagnosis of mycosis fungoides is generally benign. This uncommon situation raises the question of nosology among epidermotropic T-cell proliferations.

Two women (age 65 and 70 years, cases 1 and 2) and one man (age 66 years, case 3) each had a well-limited unique oval-shaped plaque measuring 1 to 3 cm in diameter for several months. The localization of the erythematous, squamous plaques with minimal infiltration and little or no pruritus remained unchanged in the dorsal area. Histology reported mycosis fungoides: dense superficial dermal infiltration in band attached to the epidermis with a clear lower limit, formed by small and medium-sized atypical lymphocytes, sometimes with cerebriform nuclei. Epidermotropism on isolated cells or theques was noted. There was no spongiosis. Immunolabeling demonstrated predominance of CD4+ cells and tumoral infiltration uptake of anti-V beta 8 monoclonal antibodies in the two cases examined. The lesion totally regressed in case 1 after local application of carmustine with no recurrence after 5 years. Patient 2 declined treatment and no change was observed 5 years later. Surgical exeresis was performed in case 3 without recurrence 3 years later.

No histological feature or T-cell immunophenotype distinguishes this clinical entity from classical mycosis fungoides. As no other long-term lesions developed, our three cases would argue for a benign course of what is probably a variety of mycosis fungoides. Unilesional plaque mycosis fungoides must be lymphomatoid contact dermatitis. Woringer-Kolopp disease differs by its nearly exclusive epidermotropic distribution.