A Comprehensive Update of the Atypical, Rare and Mimicking Presentations of Mycosis Fungoides

INTRODUCTION: Mycosis fungoides (MF) is the most frequent subtype of primary cutaneous T cell lymphomas (pCTCL). The diagnosis may be particularly difficult in the early stages as well as in atypical and rare clinical presentations. Furthermore, MF may simulate a large variety of common dermatologic disorders and patterns, both histopathologically and clinically. METHODS: A literature search was performed to provide a comprehensive update on the rare and atypical MF manifestations as well as the dermatoses and dermatological patterns that could be imitated by MF. RESULTS: A total of 114 publications were found describing a series of different dermatoses and dermatological patterns mimicked by MF, as well as some particular localizations of MF lesions and dermatoses that occur in preexisting MF lesions. CONCLUSIONS: The number of dermatoses that can be imitated by MF is ever-increasing. Patients with common dermatologic conditions that prove to be treatment refractory should be biopsied without delay, and sequentially as necessary, to prevent delay in diagnosis and progression of disease. Clinicopathologic correlation is the best way of diagnosis.