Renal Mass Lesion in an Adult Man

Junqi Qian, M.D.

Specimen Type:

Kidney

History:

A 44-year-old male with a renal mass underwent partial nephrectomy.

Pathologic Features:

Gross Features: Grossly, a 45 x 33 x 25 mm cystic mass is adherent to the renal medulla with intact overlying cortex. The cyst is multiloculated and the walls are tan-pink and smooth. An additional loculated area contains hemorrhagic material which is focally calcified. Representative cross-sections were submitted.

Microscopic Features: Microscopically, the tumor consists of multilocular cysts lined by a single to multi-layered epithelial cells (Fig 1, 2) and septa with no expansile solid nodules (Fig 3, 4); within the septa there are clusters of epithelial cells with clear cytoplasm and small dark nuclei (Fig 5-7). Focal calcifications are identified in the kidney (Fig 8). Tumor does not invade the renal capsule or perinephric fat.

Differential Diagnosis:

  • Cystic multilocular clear cell renal cell carcinoma
  • Conventional clear cell carcinoma
  • Segmental cystic disease
  • Mucinous tubular and spindle cell carcinoma
  • Wilms’ tumor and Cystic Partially Differentiated Nephroblastoma
  • Cystic nephroma
  • Tubulocystic carcinoma
  • Carcinoma of the collecting ducts of Bellini
  • Papillary renal cell carcinoma
  • Congenital mesoblastic nephroma

Diagnosis:

Multilocular cystic renal cell carcinoma

Key Features

  • Rare and distinctive entity recently recognized
  • It constitutes about 1-5% of all renal cell carcinomas
  • It has a male predominance with a male: female ratio of 2-3:1
  • Occurs in adults and elderly patients
  • Most patients are asymptomatic and their tumor is discovered incidentally
  • Grossly, the lesion ranges from 0.5 to 13.0 cm in greatest dimension
  • The cysts are of variable size, and contain clear or hemorrhagic fluid
  • The septa between cysts are thin
  • Low power: the cysts are lined by epithelial cells, usually as a single layer, but occasionally multi-layered, and occasionally forming minute papillary structures
  • High power: The lining cells have variable amounts of cytoplasm that may be clear or lightly eosinophilic
  • The septa consist of fibrous tissue
  • More than 20% of tumors show calcifications within the septa
  • Within the septa in all cases there are clusters of epithelial cells with clear cytoplasm
  • Ploidy studies reveal diploid DNA content in more than 90% of cases

References:

  1. Eble JN, Bonsib SM: Extensively cystic renal neoplasms: cystic nephroma, cystic partially differentiated nephroblastoma, multilocular cystic renal cell carcinoma, and cystic hamartoma of renal pelvis. Semin Diagn Pathol 15:2-20, 1998.
  2. Corica FA, Iczkowski KA, Cheng L, et al: Cystic renal cell carcinoma is cured by resection: a study of 24 cases with long-term followup. J Urol 161:408-11, 1999.
  3. Suzigan S, Lopez-Beltran A, Montironi R, et al: Multilocular cystic renal cell carcinoma : a report of 45 cases of a kidney tumor of low malignant potential. Am J Clin Pathol 125:217-22, 2006.