Poikilodermatous mycosis fungoides with a CD8+ CD56+ immunophenotype: a case report and literature review.

Mycosis fungoides (MF) represents the most common type of cutaneous lymphoma. MF shows varieties in both its clinical presentation and immunophenotype. We herein report one case of poikilodermatous MF with a CD8+ CD56+ immunophenotype and present a literature review. A 20-year-old Japanese woman presented with a 10-year history of multiple poikilodermatous and reddish or brownish patches with mild pruritus on the chest, abdomen, back, buttock and thighs. Histopathologically, small- to medium-sized atypical lymphocytes infiltrated into the epidermis, indicating epidermotropism, along the basal layer, and distributed in band-like appearance in the papillary dermis. Immunohistochemically, atypical lymphocytes expressed CD3, CD8, CD56, T-cell intracellular antigen (TIA)-1, granzyme B and beta F1 but lacked expression of CD4, CD20, CD30 and Epstein-Barr virus (EBV) latent membrane protein 1. An EBV-encoded small non-polyadenylated RNA-1 (EBER-1) signal was not detected. On the basis of these findings, the diagnosis of CD8+ CD56+ MF was established. Poikilodermatous MF with a CD8+ CD56+ immunophenotype, as presented herein, is extremely rare. Although further investigation is needed to fully clarify the nature of this aberrant phenotype of MF, we stress that it is important to recognize this rare immunophenotype of MF to distinguish it from aggressive cytotoxic cutaneous lymphomas.