Mesenchymal chondrosarcoma of kidney
A 22-years-old female complained of hematuria, high grade fever, heaviness, and pain in right flank for 2 months. Contrast enhanced computed tomography (CECT) revealed a complex hypodense mass with variegated attenuation measuring 6 × 6 × 5.6 cm in mid-polar region of right kidney, involving the inferior vena cava. No calcification or fat was noted within the mass. No perirenal infiltration or lymphadenopathy was observed. Magnetic resonance imaging (MRI) revealed a large lobular mass measuring 6.5 × 6.2 × 5.6 cm in the right kidney with mixed hyperintense and hypointense signals on T2 weighted imaging. Positron emission tomography showed some subcentimetric non-FDG avid lung nodules which were suspected to be metastatic deposits. A clinical diagnosis of right sided renal cell carcinoma (T3bN0Mx) with invasion into inferior vena cava and metastasis to lungs was made. Right radical nephrectomy with IVC thrombectomy and lymph node dissection was performed. Per-operatively, the tumor involved the medullary region of right kidney. The IVC thrombus was infiltrating its wall and extended upto the level of caudate lobe of liver.\nPathology - Grossly, the right nephrectomy specimen measured 9 × 6 × 4 cm and showed a friable tumor measuring 4 × 4 × 3 cm in the medullary region, invading the renal parenchyma and compressing the pelvicalyceal system, but not involving the latter []. The tumor was fleshy in appearance and there were no glistening areas visible within the tumor grossly. The renal vein showed a tumor thrombus. IVC thrombus, sent separately, measured 5 × 2 × 2 cm. Attached ureter measured 2 cm and was grossly free of tumor. Histopathology showed a well circumscribed tumor comprising of an unusually large component of well differentiated cartilage alternating with stromal component which comprised of small sized, oval to spindle shaped cells with moderate nuclear pleomorphism, hyperchromatic nuclei, inconspicuous nucleoli, and moderate cytoplasm [Figure and ]. The spindle shaped cells displayed a hemangiopericytoma like pattern of arrangement []. Numerous atypical mitotic figures were noted along with focal areas of myxoid change and necrosis. The tumor was not involving the pelvicalyceal lining, which showed normal morphology and displayed no features of dysplasia/carcinoma in situ. On immunohistochemistry (IHC), the spindle cells were positive for vimentin and the cartilaginous component was strongly positive for S-100 []. The tumor was involving the inferior vena cava. However, the ureter and the lymph nodes (29 in number) were free of tumor. Based on these findings, a diagnosis of extra skeletal mesenchymal chondrosarcoma of kidney was made.\nTreatment - The patient was planned for close follow up at monthly intervals. Within 3 weeks of surgery, she presented with dyspnoea and chest pain of acute onset. CT pulmonary angiography was suggestive of pulmonary thromboembolism with partial IVC thrombosis. She was started on systemic chemotherapy with intravenous Cisplatin (90 mg/m2) and Epirubicin (75 mg/m2) on Day 1 at 3 weekly intervals. After six cycles of chemotherapy, the patient showed marked clinical improvement with significant regression in lung nodules [].