Primary mesenchymal chondrosarcoma with bilateral kidney invasion and calcification in renal pelvis: A case report and review of the literature.

Mesenchymal chondrosarcoma (MC) is a rare malignant cartilaginous forming tumor. MC of the kidney is extremely rare, with only seven cases reported in the literature. The present study described the case of a 17-year-old male, who presented with sudden severe pain in the right flank and a high fever. Imaging studies demonstrated a large soft heterogeneous mass (7.8×9.5×15 cm) located between the liver and right kidney with no clear demarcation, and a well-demarcated mass (1.3×2.4 cm) with patchy dense calcification occupying the left renal pelvis. Following the diagnosis of a Wilms' tumor, the patient underwent a right radical nephrectomy and the pathological diagnosis was MC of the kidney. To the best of our knowledge, the current study presents the first case of MC with bilateral kidney invasion and calcification in the renal pelvis. In addition, the clinical, radiological and pathological features, and the management of this unusual neoplasm were discussed.