Folliculotropic mycosis fungoides

Abstract

Folliculotropic mycosis fungoides (FMF) is a variant of mycosis fungoides (MF) noted in the World Health Organization — European Organization of Research and Treatment of Cancer (WHO/EORTC) update of 2018. FMF is characterized as a subtype with a worse prognosis than classic MF. The situation changed recently when authorities proposed dividing FMF into two prognostically different subtypes: indolent and aggressive. Indolent FMF allows 92% of patients to survive five years, and 72% 10 years. But only 55% and 28% of patients with aggressive FMF can survive respectively five and 10 years. FMF with internal organ involvement on the day of diagnosis shortens lives drastically (23% survive five years, only 2% survive 10 years). There are many clinical subtypes (with plaques with follicular accentuation, alopecia, comedones, erythematous follicular papules, acneiform lesions mimicking rosacea, milia, ‘spikes’, and facial involvement known as leonine face), as well as histopathological variants (with attern with intact hair follicles, folliculotropism with or without mucinosis, basaloid folliculolymphoid hyperplasia with folliculotropism, granulomatous dermatitis associated with folliculotropism, eosinophilic folliculitis, follicular cysts with folliculotropism) of FMF. This all makes diagnosis even more difficult. Combined topical and systemic treatment can be useful, with topical corticosteroids, phototherapy, radiotherapy, bexarotene, interferon, as well as with methotrexate and brentuximab vedotin. If the disease does not respond to these therapies, allogeneic hematopoietic stem cell transplantation (allo-HSCT) should be considered. Chemotherapy (gemcitabine, liposomal doxorubicin, polychemotherapy) is often associated with a merely temporary response, and that is why it should be employed only in non-responsive cases and/or as a bridge to allo-HSCT.