Extensive calcium oxalate crystal deposition in papillary renal cell carcinoma: report of two cases.

Calcium oxalate crystals are common in renal disease; however, to our knowledge they have not been reported previously in renal cell carcinoma. We report two patients with papillary renal cell carcinoma and extensive calcium oxalate crystal deposition within the tumors. Both patients had end-stage renal disease and acquired renal cystic disease. Radiographic studies demonstrated calcifications in one case. Histologically, both tumors had papillary features and had numerous calcium oxalate crystals within cystic spaces and papillae. The presence of calcium oxalate crystals in these tumors is additional evidence that papillary renal cell carcinomas and acquired cysts may be related.