RESUMO
Plasmablastic lymphoma (PBL) is a rare lymphoma originating from B-cells with terminal differentiation. Most common anatomic site involved by PBL is the oral cavity. Involvement of other body sites has only rarely been reported. Herein, we report a rare case of EBV-negative PBL involving the breast of an HIV positive 47-year-old woman. The patient presented with decreased vision and photophobia. During physical examination, she was found to have bilateral breast masses and multiple lymphadenopathy. Fine-needle aspiration of one of the breast masses showed large malignant cells with plasmacytoid features. Immunohistochemical studies performed on the core biopsy showed that the tumor cells were positive for common leukocyte antigen CD45 and plasma cell marker CD138, but negative for the pan-B cell markers CD20 and CD79a. Molecular genetic studies showed clonal rearrangement of the immunoglobulin kappa light chain gene. This is the first case of PBL involving the breast reported in English cytological literature.