Posttransplant Kaposi’s Sarcoma Restricted to the Site of a Previous Deep Venous Thrombosis: Abrupt Onset after Withdrawal of Sirolimus

Abstract

Kaposi's sarcoma (KS) is an angioproliferative neoplasia associated with human herpesvirus 8 (HHV-8) infection. HHV-8 generates KS by means of the secretion of vascular endothelial growth factor (VEGF) andup-regulation of VEGF receptor, KDR, in endothelial cells. We report a case of KS in a 72-year-old male with a renal transplant who had received immunosuppressant drugs including sirolimus, mycophenolate mofetil, tacrolimus and steroids. KS developed 11 months after transplantation, in relation to deep venous thrombosis and withdrawal of sirolimus due to toxicity. Multiple purple papules and nodules were observed exclusively in the limb affected by thrombosis. Diagnosis of KS was confirmed by biopsy. Progressive withdrawal of prednisone was accompanied by full remission of the tumour. The thrombosis and withdrawal of sirolimus may have acted as cofactors in the development of KS, favouring the activation of the VEGF/KDR autocrine loop. Our experience contributes to further evidence that sirolimus may protect against KS.