Epstein-Barr virus-positive plasmacytoma in immunocompetent patients: a diagnostic dilemma.

By literature review, plasmacytomas arising in immunocompetent patients are rarely associated with Epstein-Barr virus (EBV) infection. EBV-positive plasmacytoma can cause a diagnostic dilemma as it may morphologically and phenotypically overlap with a clinically aggressive plasmablastic lymphoma (PBL). We reported the clinicopathologic and immunophenotypic findings of four patients with EBV-positive plasmacytomas (three cases of extramedullary plasmacytomas, one case of solitary plasmacytoma of bone) with immunocompetent status. These tumors were characterized by a diffuse proliferation of mature appearing plasma cells, which were diffusely positive for EBV encoded RNA (EBER) by in situ hybridization. All the four patients were alive with no evidence of disease at last follow-up.