Abstract

Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma and can present with a wide range of clinical and pathological features. A 72-year-old male presented with tender, scaly plaques on the dorsal and palmar aspects of the hands and fingers, initially felt to represent viral verruca. Prior to presentation, the patient had been treating the lesions unsuccessfully as hand dermatitis with topical clobetasol for almost a year. Biopsies of two lesions on the left hand both revealed prominent spongiotic vesicles, mimicking dyshidrotic dermatitis. An atypical lymphoid infiltrate tagging the dermal-epidermal junction and forming intraepidermal microabscesses was observed. The lesional lymphocytes were hyperchromatic and had convoluted nuclear contours. The lymphocytic infiltrate expressed CD4 and CD8 at a ratio of at least 10:1 with loss of CD7 expression. T-cell receptor gene rearrangement studies performed on both biopsies showed identical clonal rearrangements of the T-cell receptors, both gamma and beta. A colloidal iron tissue stain was subsequently performed highlighting prominent intraepidermal mucin within the spongiotic foci. Based on the histopathologic findings, the diagnosis of acral MF with spongiotic vesiculation and mucinosis was made. While slight spongiosis can be seen in MF, substantial spongiosis and vesiculation is rare, which can lead to misdiagnosis in favor of an inflammatory dermatosis. In cases of MF with prominent spongiosis, the presence of substantial mucinosis may serve as a helpful clue in the histopathologic evaluation.

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