[Kaposi's sarcoma following kidney transplantation: remission following reduction of immunosuppression and consequent HIV infection].

Kaposi's sarcoma (KS) in renal allograft recipients is a rare though serious complication of immunosuppressive treatment. Therapeutic procedures such as surgical excision and local irradiation are inappropriate, since the endothelial-originated tumor is often multicentric. However, systemic treatment such as chemotherapy entails further immunosuppression. We observed a patient with renal allograft who developed disseminated KS of legs and trunk while receiving azathioprine, cyclosporin and prednisone after intensive rejection therapy with high dose corticosteroids, antithymocyte globulin and transplant irradiation. At that time the immunological status was similar to that of an AIDS patient, though HIV serology was negative. Azathioprine was withdrawn while cyclosporin and prednisone were continued. KS disappeared shortly after without a decrease in allograft function, and immunological parameters tended to normalize. When KS had disappeared almost completely the patient became infected with HIV. Complete remission was not hampered, nor was there recurrence of KS. The late appearance of HIV-antigenemia with seroconversion in the course of the tumor makes HIV unlikely as a causative factor. The predisposing factors for KS after renal transplantation are discussed: 1. Amplification of immunosuppression due to rejection therapy, 2. Genetic predisposition such as HLA DR5 antigen, 3. Cytomegalovirus infections. For therapy of iatrogenic KS we propose reduction of immunosuppressive therapy before additional chemotherapy is initiated.