Cytotoxic Variant of Mycosis Fungoides with CD8+ CD56+ Phenotype: A Case Report and Review of Literature.

Mycosis fungoides (MF) is the most common cutaneous Tcell lymphoma. Approximately 50% of all primary cutaneous lymphomas are MF[1]. These lymphomas are comprised of epidermotropic collections of small- to medium-sized T lymphocytes with cerebriform nuclei. The neoplastic cell shows a mature CD3+, CD4+, CD45RO+, CD8– memory T-cell phenotype. However, rarely, MF with a CD4–, CD8+ cytotoxic T-cell phenotype has been reported[2-5]. The World Health Organization (WHO)-European Organization for Research and Treatment of Cancer (EORTC) classification for cutaneous lymphomas describes three types of cutaneous lymphomas that express CD56: 1) subcutaneous panniculitis-like T-cell lymphoma, 2) extranodal natural killer (NK)/T-cell lymphoma, nasal type, and 3) CD4+/CD56+ hematodermic neoplasm (blastic NKcell lymphoma)[1]. However, the report does not mention, MF with CD56 expression. Earlier in 2003, a report by the EORTC cutaneous lymphoma task force workshop described cytotoxic/natural killer cell cutaneous lymphomas and divided them into eight categories[6]. One of these categories was the CD56+, cytotoxic variant of MF. This report presents a rare CD8+, CD56+ variant of MF having the cytotoxic phenotype.