Pediatric follicular mucinosis: presentation, histopathology, molecular genetics, treatment, and outcomes over an 11-year period at the Mayo Clinic.

Follicular mucinosis (FM) and folliculotropic mycosis fungoides (MF) are rare in children, and data regarding long-term outcomes are limited. We sought to describe clinical and histopathologic findings of children with FM with and without MF, as well as treatments administered and clinical outcomes. We conducted a retrospective chart review of patients younger than 22 years (at time of diagnosis) with a biopsy demonstrating FM who were seen in the Dermatology Department at the Mayo Clinic from September 1, 1999, to September 1, 2010. Eleven patients (six male, five female) ages 11 to 19 years at the time of diagnosis met the inclusion criteria. Follow-up data were available for 10 patients, with a mean duration of 4.9 years. The head, neck, and extremities were the most common sites of involvement, and lesions were follicular-based papules (18%), scaly alopecic patches and plaques (45%), or a combination of the two (36%). Overall, three patients were confirmed to have MF. T-cell receptor gene rearrangement demonstrated clonality in two cases and was equivocal in one case. Treatments included topical corticosteroids, topical retinoids, oral minocycline, and, in patients with MF, ultraviolet light and topical bexarotene. Lesions resolved completely in seven patients, partially in one, and not at all in two (no follow-up data on one patient). Of the three patients with MF, two had complete resolution, and one has intermittent flares. To our knowledge, no patients developed other lymphoproliferative disorders. FM in children is rare. A histopathologic diagnosis of FM does not equate to folliculotropic MF in all cases. Most patients responded to treatment with topical steroids, topical retinoids, or phototherapy. In our series of patients, the disease ran a benign course.