Primary renal osteosarcoma: A case report

Primitive renal osteosarcoma is a rare sarcoma of the kidney with only 27 cases reported in the literature. Its histogenesis is poorly understood. It occurs at an older age between the fifth and seventh decade of life with a male predominance. The clinical features are similar to other renal diseases. Imaging shows calcifications within a lumbar or flank mass. Histology describes a sarcomatous proliferation producing osteoid, most often at an advanced stage (pT4), which implies a poor prognosis. We report on the clinical and pathologic features of a case of primary renal osteosarcoma in a 56-year-old man with stage IV disease. This is the 28th case of primitive renal osteosarcoma reported in the literature, confirming the highly malignant nature of this tumor and the need for early diagnosis.