Blastic NK-Cell Leukemia / Lymphoma

Blastic natural killer (NK) cell lymphoma / leukemia is a rare NK cell malignancy of unknown etiology. It occurs in multiple sites and with a propensity for skin involvement. We report such a case in a 35-year-old male suffering from erythematous and purpuric papules and plaques on his face and trunk for 6 months. A biopsy specimen of the skin showed diffuse infiltration of blastlike lymphoid cells in the dermis and subcutis. Immunohistochemical study showed the tumor cells were only positive for CD56 and CD45 and negative for other T-cell, B-cell, and myeloid cell markers. T-cell receptor (TCR) gene rearrangement was germline. In situ hybridization for Epstein-Barr virus (EBV) encoded small ribonucleic acid was negative. Aspiration specimen of the bone marrow revealed diffuse infiltration of CD56 + lymphoid cells in interstitial spaces. The diagnosis of a blastic NK-cell lymphoma / leukemia was made. Because of its rarity, the case is reported. (Dermatol Sinica 21 : 408-412, 2003)