Plasmablastic lymphoma involving the breast: report of a case and review of literature

Background: Plasmablastic lymphoma (PBL) is a rare entity of non-Hodgkin lymphomas that usually occurs in the oral cavity in immunocompromised patients. PBL involving the other sites have rarely been reported. Case report: Herein, we report a rare case of EBV-negative PBL in the left breast of an immunocompetent 56-year-old woman. During physical examination, she had left breast masses and left axillary lymphadenopathy. After surgical resection of the neoplasm, histological and cytological examinations were performed and the tumor was diagnosed to be primary PBL. Tumor cells expressed VS38c and some were MUM1-positive, but were negative for common leukocyte antigen CD45, pan-B cell markers CD20 and CD79a, plasma cell marker CD138, EMA, CD38, CD56, PAX5, ALK. Ki-67 immunostaining showed a proliferation index of 80%. Gene rearrangement analysis showed positive B lymphocyte gene IGH and IGK rearrangement in the bone marrow. Bone marrow biopsy was negative for marrow infiltration. Patient received modified CHOP chemotherapy after the surgery and was responding well. Conclusions: Accurate diagnosis of this PBL case relied on the histological morphology of the tumor cells, immunohistological markers and gene rearrangement tests. Despite the poor prognosis of PBL, surgical resection of the tumor combined chemotherapy maintains a stable state of the patient 6 months from the diagnosis. Accumulation of more cases could guide future diagnosis and treatment choices for this rare disease.