Multilocular cystic renal neoplasm of low malignant potential

Case contributed by Ammar Ashraf
Diagnosis certain


Right loin pain for a few months. No hematuria, fever, or weight loss. Known hypertensive for the last 12 years.

Patient Data

Age: 30 years
Gender: Male

A well-defined, rounded, complex lesion having both solid and cystic components measuring 3.5 x 4.0 cm is noted at the mid pole of the right kidney. The lesion is splaying the adjacent vessels; however, no internal vascularity is seen in it on doppler ultrasound examination. No calcifications are seen in it.

A well-defined rounded cystic lesion measuring 4.5 x 5.0 x 4.5 cm is noted at the mid pole of the right kidney.  The lesion is hypointense on T1W and hyperintense on T2WI, has relatively thick wall and internal septations, and shows no diffusion restriction. Post-contrast scan shows enhancement of the wall and the septae which is equal to the renal parenchyma.  No solid component, or hemorrhagic contents are seen in it. Small L3 vertebral body lesion (bright on both T1 and T2-weighted images) suggestive of hemangioma. Impression: Right renal cystic lesion with relatively thick enhancing wall and septae (Bosniak type 3 cyst). 

A complex cystic lesion having thick irregular enhancing septations, measuring about 5.5 x 4.5 cm is seen at the lower pole of the right kidney. Renal vessels and IVC are patent. No loco-regional or distant metastases are seen. Impression: Complex right renal cystic lesion suggestive of Bosniak type 3 cyst.

Case Discussion

Pre-operative diagnosis: Right renal mass.

Procedure: Right partial nephrectomy.

Diagnosis: Multilocular clear cell renal cell carcinoma. Maximum tumor size = 5cm (4 x 4 x 5 cm). Histologic grade (FUHRMAN nuclear grade) = G2. Tumor is limited to the kidney. Margins free. Perinephric tissue, pelvicalyceal system, and adrenal gland invasion cannot be determined (no perirenal tissue, pelvicalyceal tissue & adrenal gland is submitted). Negative for capsular, vascular and perineural invasion.

Pathologic staging: pT1b, pNX, pMX.

Other findings: Non-neoplastic kidney shows chronic interstitial nephritis especially in the region adjacent to tumor.

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