Hyperpigmented skin lesions rarely appear as a specific manifestation of mycosis fungoides (MF).

To study the clinical, histopathological, and immunohistochemical features of hyperpigmented MF.

Patients with hyperpigmented MF were identified by a file search of all patients with MF who had attended a cutaneous lymphoma outpatient clinic in the last 15 years, and the relevant data were collected.

Eight patients had early-stage MF manifested by hyperpigmented patches and/or flat plaques. All but one had a dark complexion. Mean age at diagnosis was 43 years (range, 19-69), and mean interval from disease onset to diagnosis was 6.25 years (range, 1-14). In 5 patients, the hyperpigmented lesions were the sole manifestation of the disease; in the remainder, they appeared in conjunction with other unusual lesions of MF. Histologically, all our patients had interface changes with melanophages in addition to the classical findings of early MF. Only one patient had a CD4⁺ epidermotropic T-cell phenotype; 5 patients had a CD8⁺ phenotype, and 2 had a CD4⁻CD8⁻ phenotype. Patients received skin-targeted therapies, and all had indolent course without evidence of disease progression after a mean follow-up of 3.8 years.

This was a case series descriptive study.

Hyperpigmented MF is an atypical clinical variant of cutaneous T-cell lymphoma, with a predilection for patients with a dark complexion. It is characterized by a predominantly CD8⁺ phenotype. Hyperpigmented lesions may be the sole manifestation or it may coexist with other unusual MF variants typified mostly by pigmentary changes.