T-follicular-helper phenotype mycosis fungoides associated with acanthosis nigricans.

The association between acanthosis nigricans (AN) and mycosis fungoides (MF) has rarely been described, but it is known that MF may appear as AN-like vegetating and papillomatous plaques in skin folds, or may be associated with paraneoplastic AN. There have also been recent descriptions of a form of "intertriginous MF" that is characterised by skin fold involvement and the expression of T follicular helper (TFH) markers, and often has an aggressive course. We describe the case of a 48-year-old man affected by MF associated with AN, whose lesions were characterised by a TFH immunophenotype and the expression of the GATA-3 nuclear master regulator that may be related to a TFH-2 sub-population or possible disease progression. This article is protected by copyright. All rights reserved.