MYCOSIS FUNGOIDES (MF): THE MASTER OF MIMICRY

Abstract

<h3>Introduction</h3> Mycosis fungoides (MF) is the most common form of primary cutaneous T-cell lymphomas, characterized by a long clinical course and malignant T-cell proliferation. The early stages of MF can mimic atopic dermatitis (AD), and psoriasis and thus, diagnosis can be challenging and oftentimes delayed. <h3>Case Description</h3> A 39-year-old African American female with developmental delay was referred for a mildly pruritic, generalized eczematous dermatitis, hyperkeratosis of the palms and soles, and contractures with fingernail clubbing. Skin biopsy two years prior was reportedly unremarkable. Treatment for an initial diagnosis of fungal dermatitis with mupirocin, clotrimazole, and lotrisone was started with regular debridement of the feet. Rheumatological workup was negative, including x-rays of the hands and chest. Clobetasol wraps provided short-term relief. Dupixent for AD was discussed but not started. A second skin biopsy ultimately revealed erythrodermic MF. Flow cytometry was compatible with Sezary syndrome and T-cell receptor gene rearrangement study was positive for monoclonal gene rearrangement. <h3>Discussion</h3> MF diagnosis is not easy, primarily due to the atypical clinical presentation of the disease at an early stage, and non-specific changes on histopathology. As such, multiple biopsies may be needed to make a diagnosis. This case highlights important points for the allergist. 1) Erythema in skin of color is hard to appreciate 2) MF can often look like AD and 3) Palmoplantar Keratoderma may be associated with MF.