Clinicopathological analyses of 5 Japanese patients with CD56+ primary cutaneous lymphomas

We analyzed the clinicopathological features of 5 Japanese patients with CD56+ primary cutaneous lymphomas (3 men and 2 women aged 25 to 73 years). Except for 1 patient in whom bone marrow involvement was simultaneously observed, all patients presented with cutaneous lesions. Based on their Epstein-Barr virus (EBV) status, we categorized these patients into 2 groups, namely EBV-encoded small RNA-1 (EBER-1) (3 patients) and EBER-1- (2 patients). Generalized lymphadenopathy and bone marrow involvement were observed only in EBER-1 patients. Morphologically, angiocentric proliferation was more prominent in EBER-1+ patients and was accompanied by panniculitis-like changes. The lymphomas in EBER-1- patients featured monomorphic proliferation of lymphoblastic cells with no cytoplasmic granules. Phenotypically, CD3-, cytoplasmic CD3 epsilon+, and CD56+ were common findings in both types. The EBER-1- type showed an additional distinguishing feature, CD7+, CD4+, CD8-, HLA-DR+, and terminal deoxynucleotidyl transferase-positive (TdT+) phenotype. The lymphoma was primarily resistant in the EBER-1+ type, and the patients died within 6 months of admission. In contrast, the lymphoma in the EBER-1- patients was originally chemosensitive. Collectively, we consider there to be at least 2 types of CD56+ primary cutaneous lymphomas, corresponding to nasal-type natural killer (NK)/T-cell lymphomas (EBER-1+) and blastic NK-cell lymphomas (EBER-1-).