[Diffuse large B-cell lymphoma concurrent with Kaposi's sarcoma in the same lymph node in a human immunodeficiency virus-negative patient].

An 80-year-old Japanese man presented with systemic lymphadenopathy, including the para-aortic area and left inguinal nodes, which was diagnosed as diffuse large B-cell lymphoma (DLBCL) and human herpesvirus (HHV) 8-positive/HIV-negative Kaposi's sarcoma (KS). Immunohistochemical examination revealed that the lymphoma cells were negative for HHV-8. The patient received combined chemotherapy with rituximab, pirarubicin, cyclophosphamide, vincristine, and prednisolone for six cycles and achieved complete remission. In the literature, five cases of simultaneous appearance of malignant lymphoma and KS in the same lymph node have been reported, but DLBCL as a histological subtype has not yet been reported.