Human immunodeficiency virus-negative plasmablastic lymphoma in Korea.

Plasmablastic lymphoma (PBL) is very rare, and predominantly occurs in Human immunodeficiency virus (HIV)-positive individuals. It shows a strong affinity for the oral cavity and for the Epstein-Barr virus (EBV) positive. We investigated the clinicopathologic characteristics of six cases of PBL in Koreans. All patients were HIV-negative and without underlying immunodeficiency. The age distribution was bimodal, and four patients were older than 60 years. Male predominance was observed with male to female ratio of 5:1. The organs primarily involved were the terminal ileum, stomach, oral cavity, tonsil, nasal cavity and meninges. The tumors were histologically typical of PBL. Three of them were composed of monomorphic large immunoblastic or plasmablastic cells, and classified as PBL of the oral mucosa type. Another three cases were classified as PBL with plasmacytic differentiation. Five cases revealed loss of B-cell antigens with CD138 or MUM1 substitution. CD10 was positive in two cases (PBLs of the oral mucosa type), and one of them unexpectedly expressed cytokeratin. EBV was detected in one case (PBL with plasmacytic differentiation). Four patients succumbed to PBL in a relatively short period of time. We suggest that PBL is not strongly associated HIV or EBV in Koreans, and that it shows a variable organ distribution without an oro-nasal predilection.