Underrecognized clinical features of folliculotropic mycosis fungoides: a large clinical series

Background and Objective: A rare variant of mycosis fungoides (MF), folliculotropic MF (FMF) is characterized by a broad clinical spectrum that primarily includes follicle-based lesions but also many atypical clinical manifestations. The objective of the present study was to conduct a clinical analysis of patients with FMF, with a particular focus on highlighting underrecognized dermatological features. Patients and Methods: Overall, 27 FMF patients enrolled in our department's MF registry, which includes 572 patients, were retrospectively reevaluated with regard to demographics, clinical features, treatment modalities, follow-up, and outcomes. Results: Besides the well-known clinical features of FMF, we found lichen spinulosus-like lesions in association with hypopigmentation (n = 3) and alopecia (n = 2), infiltrated/elevated erythematous facial plaques initially considered to be lupus tumidus (n = 2), pseudotumoral lesions clinically mimicking tumor-stage MF (n = 1), persistent excoriations (n = 1) and erythematous facial papules mimicking rosacea (n = 1), as well as white dome-shaped asymptomatic papules/nodules filled with mucin (on histology) (n = 2) that overlay other disease-related lesions. Various therapeutic methods were used with variable results. Eight (29.6 %) patients had late-stage disease. Conclusions: Awareness of underrecognized clinical manifestations may be key to reducing delayed diagnosis of this aggressive MF variant.