How is renal cell carcinoma differentiated from Wilms tumor on imaging?

Updated: Mar 04, 2019
  • Author: Ali Nawaz Khan, MBBS, FRCS, FRCP, FRCR; Chief Editor: Eugene C Lin, MD  more...
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Renal cell carcinoma is a primary epithelial neoplasm that arises from the proximal convoluted tubule. Nearly all cases occur in adults, though the carcinoma has been recorded in children younger than 10 years. Early cases are seen as small, cortical-based masses that enlarge and invade the renal parenchyma. Late cases may cause a classic triad of loin pain, flank mass, and hematuria. Approximately 5% of patients have bilateral tumors, though not usually simultaneously.

Appearances vary widely and depend on the size of the tumor, which may be solid, cystic, or complex. Solid tumors transmit sound waves poorly; therefore, acoustic transmission is unchanged or decreased compared with that of a normal kidney. The most common appearance is increased echogenicity, which corresponds to areas of increased vascularity seen on angiography. Small tumors are particularly echogenic, so small angiomyolipomas cannot be distinguished on sonograms.

Small, hyperechoic renal cell carcinomas may have a hypoechoic rim caused by the tumoral pseudocapsule, and it may contain small, anechoic areas. No true capsule is present, and the tumor margins are irregular. Large tumors tend to hypoechoic. About 6-20% show evidence of calcification.

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