Bilateral renal metastases from extraskeletal mesenchymal chondrosarcoma of thigh.

Mesenchymal chondrosarcoma (MC) is a rare cartilaginous tumour that occurs in the extraskeletal locations in about one-third of cases. It is aggressive in behaviour and may involve the lower extremities, central nervous system or spine. Mesenchymal tumours are known for distant metastasis; however, metastasis to bilateral kidneys after treatment has not been reported earlier. We present a case of a soft-tissue intramuscular MC of the thigh in a 38-year-old patient which had been surgically excised after neoadjuvant chemotherapy. The patient presented with bilateral dense calcified renal masses after 6 years, which were cytologically proven as MC metastases. In the evaluation of bilateral calcified renal masses in patients with a history of MC, metastasis should be considered.