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

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Mycosis fungoides (MF) is the most common cutaneous T-cell lymphoma. Approximately 50% of all primary cutaneous lymphomas are MF. 1 These lymphomas are comprised of epi-dermotropic collections of small-to medium-sized T lympho-cytes 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. The World Health Organization (WHO)-European Organization for Research and Treatment of Cancer (EORTC) classification for cutaneous lympho-mas 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 NK-cell 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+, cyto-toxic variant of MF. This report presents a rare CD8+, CD56+ variant of MF having the cytotoxic phenotype. A 40-year-old male presented with a 5-year history of multiple round erythematous to dusky, brownish scaly patches with mild pruritus (Fig. 1). The skin involvement measured about 30% of total body surface. The lesions appeared first on the buttock and thigh, and lately on the upper arm. The skin lesions did not respond to topical corticosteroid treatment, at which time, he visited our hospital. A skin biopsy was taken from the thigh. The specimen showed a prominent band-like lympho-cytic infiltration in the superficial dermis with epidermotropism (Fig. 2A). The epidermotropic lymphocytes were small-to medium sized with an irregular nuclear membrane and coarse chro-matin (Fig. 2B). The immunophenotype of the cells in the epi-dermis and a few cells in the superficial dermis were CD3+, CD4–, CD8+, CD56+, CD30–, and CD20– (Fig. 2C, D). The majority of lymphocytes in the superficial dermis were not atyp-ical, in contrast to the epidermotropic lymphocytes, and were positive for CD4 and CD8. The neoplastic cells were positive for beta F1 (a marker of alpha/beta T lymphocytes) and granzyme B. An Epstein-Barr virus–encoded small non-polyadenylated RNA-1 (EBER-1) signal was not detected. Lactate dehydrogenase was elevated to 432 IU/L (range, …