Plasmablastic lymphoma (PBL) is a recently described aggressive B-cell neoplasm, which usually manifests as a localized disease of the oral mucosa in individuals infected with human immunodeficiency virus (HIV). Recently we encountered a case of plasmablastic lymphoma manifesting in the left maxillary sinus and cervical lymph node of a previously healthy HIV-negative man, 48 years of age. we conducted a fine-needle aspiration smear of the cervical lymph node, and this was found to be highly cellular with numerous large cells exhibiting eccentrically positioned nuclei, prominent nucleoli, and moderate quantities of basophilic cytoplasm. A biopsy of the mass in the maxillary sinus evidenced diffuse growth of similar plasmablastic cells. These tumor cells were negative for the leukocyte common antigens, CD20, CD3, CD30, and EMA. However, the cells tested positive for CD79a and CD138/syndecan-1. The tumor cells also exhibited L-light-chain restriction. The Ki-67 proliferation index was measured at almost 100%. The patient was diagnosed with plasmablastic lymphoma. After three cycles of combination chemotherapy and radiotherapy, the patient went into complete remission, and currently remains in this state.