Abstract:

Mycosis fungoides (MF) is a primary cutaneous T cell lymphoma. Although histopathologic findings may vary, there is generally epidermotropism with little to no spongiosis. The histologic finding of intraepidermal lymphocytes out of proportion of spongiosis is therefore a helpful clue to making the diagnosis. Mucinous deposits are commonly found in follicular mucinosis as well as the folliculotropic variant of MF. Yet, they are rarely described within the epidermis and non-follicular epithelium. Some cases of MF however may have epidermal mucinosis in a spongiotic pattern mimicking an eczematous process. Herein, we describe a case of acral MF with mucinous spongiosis. Our patient presented with a persistent, one year history of palmar and plantar dermatitis unresponsive to dupixent. Histopathology was striking for psoriasiform hyperplasia with a brisk lymphocytic infiltrate characterized by an elevated CD4:CD8 and prominent intraepidermal spongiotic-like vesicles. Alcian blue confirmed the presence of mucin within intraepidermal vesicles. T-cell receptor gene rearrangement studies by PCR were positive for a monoclonal T-cell population. To our knowledge this is the first report of MF with intraepidermal mucinosis mimicking long standing acral eczematous process.

Financial Disclosure:
No current or relevant financial relationships exist.

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Ania Henning, MD