HHV8-positive diffuse large B-cell lymphoma, NOS (HHV8+ DLBCL, NOS; also termed HHV8-positive diffuse large B-cell lymphoma DLBCL) is a DLBCL in which Kaposi's sarcoma-associated herpesvirus-infected, medium- to large-size neoplastic B-cells that resemble lymphocytes or immunoblasts infiltrate lymph nodes (~80% of cases) and, when disseminated (20% of cases), the liver and spleen. This infiltration usually disrupts the normal architecture of the involved tissues. HHV8+ DLBCL develops in HIV-infected individuals in ~50% of cases, in individuals with multicentric Castleman disease, plasma cell variant in uncommon cases, and in individuals with Kaposi sarcoma in rare cases. HHV8+ DLBCL commonly takes an aggressive course and has a poor prognosis.