Abstract
Based on the literature, there are only three reports available to date on synchronous Kaposi sarcoma (KS) and renal cell carcinoma (RCC), at least to the best of our knowledge. The present study reports a rare case of synchronous classic KS and clear cell RCC. A 69-year-old male presented with painful, purplish nodular lesions on the dorsal aspect of his hands and feet. He had no chronic medical illnesses or prior surgical interventions. An excisional biopsy of one of the lesions revealed a nodular dermal lesion with numerous vascular channels and interlacing spindle cells. A 2.5 cm-enhancing mass was found in a contrast-enhanced computed tomography scan of the abdomen, suggesting RCC or metastasis. A partial nephrectomy was performed, and the histopathological findings were consistent with clear cell RCC. The patient responded well to paclitaxel and topical imiquimod (5%), and the skin lesions disappeared. Both KS and RCC are vascular tumors, and their pathogenesis is commonly affected by an angiogenic factor known as vascular endothelial growth factor (VEGF). A complete response of KS was observed after sorafenib, an inhibitor of VEGF receptors, was administered for the treatment of metastatic renal cancer. This reinforces the fact that there is a common therapeutic and pathogenetic pathway between these two neoplasms. Synchronous KS and clear cell RCC are rare findings. Their simultaneous appearance may be triggered by the common enhancing angiogenic factor, VEGF.