Blastic natural killer (NK) cell
lymphoma is a rare
neoplasm characterized by blastoid
tumor cells expressing CD4 and CD56, with predominant skin involvement. Although this
tumor has been regarded as a
neoplasm related to NK cell, recent studies suggested that it is derived from plasmacytoid dendritic cells, but not from NK cell. Herein we report 4 cases of CD4+CD56+ lineage marker-blastic NK cell
lymphomas with a review of literatures. The patients were 3 men and one woman. Three of them were young (17, 18, and 22 yr old). Three patients had skin lesions, at initial presentation in two patients and during the course of disease in other patient. Histologically,
tumors consisted of monotonous medium to large blastoid cells showing no
necrosis, angiocentric growth or epidermotrophism. All four
tumors were CD4+ and CD56+. Three expressed
CD68 antigen. Lineage specific markers for B- and T cell were negative. All
tumors did not express
myeloperoxidase. T-cell receptor gene rearrangement, EBV, CD13 and CD33 were negative. In one patient,
tumor cells arranged in Homer-Wright type pseudorosette and expressed
terminal deoxynucleotidyl transferase(TdT). Despite the standard
lymphoma chemotherapy, the
tumors, except one lost during follow-up, progressed and relapsed. The patients died 8-60 months after diagnosis.