Hyperpigmentation as a peculiar presentation of mycosis fungoides

Hyperpigmented mycosis fungoides is an extremely rare subtype of mycosis fungoides. It presents as multiple pigmented macules and patches without poikilodermatous changes and characterized by a CD8+ phenotype on immunohistochemistry. This report describes a typical case of hyperpigmented mycosis fungoides in a 62-year-old woman, who presented with a 7-year history of multiple hyperpigmented macules and patches on the trunk and right leg with progression over this half a year. Histology and immunohistochemical staining of skin samples confirmed the diagnosis of mycosis fungoides. She received psoralen plus ultraviolet A (PUVA) therapy. After an 8-week treatment, the erythematous changes cleared without recurrence during a 6-month follow-up period. An intractable hyperpigmented patch should raise the clinical suspicion of mycosis fungoides with sequential skin biopsy.