Folliculotropic mycosis fungoides (MF) is a rare variant of cutaneous T-cell lymphoma in which the neoplastic T lymphocytes display tropism for the follicular epithelium.

To better categorize this rare form of cutaneous T-cell lymphoma we evaluated the clinical, pathological, and immunophenotypic findings, and the response to therapy and course of the disease.

Folliculotropic MF cases were selected from the registry of the Thematic Network of Cutaneous Lymphoma of Barcelona (Spain) from 1988 to 2007.

Twenty patients (11 male, 9 female) with a mean age of 54 years were included. Mean follow-up time was 43 months. The most common sites of involvement were the head and neck (80%), upper extremities, and thorax. Infiltrated plaques (55%), acneiform lesions (comedo-like and epidermal cysts) (45%), and follicular keratosis-pilaris–like lesions (45%) were the more prominent features. Histopathological findings included selective infiltration of the follicular epithelium by atypical lymphocytes in all cases. Mucinous degeneration of the follicular epithelium occurred in 60% of cases. Psoralen plus ultraviolet A therapy was the treatment of choice in the majority of patients, but these patients did not respond as well as patients with classic MF. Radiotherapy (local or total skin electron beam) was found to be the most effective treatment. A good response to bexarotene was seen in some patients.

This was a case series descriptive study.

Folliculotropic MF is a rare but well-defined clinicopathological variant of MF. Although refractory to standard therapies used in classic MF, most of our patients showed only slow disease progression.