Double-positive CD4/CD8 mycosis fungoides: a rarely reported immunohistochemical profile

Mycosis fungoides (MF) represents the most common epidermotropic cutaneous T-cell lymphoma (CTCL), and tumor cells typically express a mature T-helper memory phenotype. A minority of MF patients display an unusual phenotype, which may be either CD4(-)/CD8(+) or double negative. Herein, we report a case of biopsy-proven MF in a 31-year-old woman who presented with infiltrated plaques involving photoprotected areas of the skin. Immunohistochemical study combined with confocal microscopy revealed co-expression of CD4 and CD8 in a subset of atypical T lymphocytes. To our knowledge, this is the second report of a CD4/CD8 dual-positive MF.