Succinate Dehydrogenase–Deficient Renal Cell Carcinoma With Sarcomatoid Features

Abstract

Abstract Succinate dehydrogenase (SDH) complex deficiency syndrome is an autosomal dominant syndrome with mutations in the SDH gene characterized by multiple tumor types, including paragangliomas, pheochromocytomas, gastrointestinal stromal tumors, thyroid tumors, testicular seminoma, neuroblastomas, and, less commonly, renal cell carcinoma. SDH-deficient renal cell carcinoma is a distinct and rare subtype of renal cell carcinoma, typically with a good prognosis, that demonstrates histologic features including cytoplasmic inclusions and vacuoles with a loss of SDH subunit B immunostaining. We present a case of succinate dehydrogenase–deficient renal cell carcinoma with sarcomatoid features in a 24-year-old male who initially presented with hematuria and flank pain. An MRI of the abdomen showed a large enhancing mass in the upper pole of the kidney. He underwent a radical nephrectomy and was found to have an 11.0 × 10.5 × 10.2-cm variegated and lobular mass in the upper pole of the kidney. Microscopic examination showed sheets of cells with cleared out cytoplasm, cytoplasmic inclusions, and vacuoles. Areas of the mass showed sarcomatoid features and necrosis. The mass extended into the pelvicalyceal system and metastasized to the adrenal gland. An SDH B immunostain was performed on the specimen and was negative, confirming the diagnosis of SDH-deficient renal cell carcinoma. Subsequently, the patient underwent genetic testing and was found to have an SDHB germline mutation.