De Novo Human Herpesvirus 8 Tumors Induced by Rituximab in Autoimmune or Inflammatory Systemic Diseases.

Objective: Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma (KS)-associated herpesvirus, is involved in KS and other tumors, including multicentric Castleman's disease and primary effusion lymphoma. Rituximab (RTX) is currently used for the treatment of several autoimmune or inflammatory diseases and humoral organ transplant rejection. De novo HHV-8 tumors induced by RTX used for these indications have not been reported previously.