Mycosis fungoides masquerading as a pigmented purpuric dermatosis

Abstract

Mycosis fungoides (MF) is a cutaneous manifestation of T‐cell lymphoma, with many rare forms that are poorly understood. One subtype, purpuric MF, has significant overlap with a benign group of conditions known as pigmented purpuric dermatoses (PPD). The literature is sparely populated with cases linking PPD to MF, and generally fall into one of three categories: MF mimicking PPD (1), PPD evolving into MF(2) and PPD mimicking MF (3).

We intend to present an oral case of a 51 year old immunocompetent man who presents with multiple erythematous to rust coloured eruptions who was initially diagnosed and treated as PPD. Through histology, his case became more complex as the pathologist suggested features of MF. We discuss the results of his T cell gene rearrangement studies and new diagnosis of purpuric MF. This case aims to draw discussion from our colleagues about their experience with this rare subtype of MF, and to draw suggestions which can help clarify the natural timeline of this poorly understood condition.