Sarcomatoid acquired cystic disease-associated renal cell carcinoma.

In this article, we report a rare case of hitherto undescribed acquired cystic disease (ACD)-associated renal cell carcinoma (RCC) with sarcomatoid change. A 78-year-old woman had been receiving hemodialysis for fourteen years at the time when a renal tumor was encountered on the follow-up examination of the kidney. Microscopically, oncocytic cuboidal cells proliferated with tubular, cribriform or papillary growth patterns, and atypical columnar cells with abundant cytoplasm proliferated with papillary configuration. Oxalate crystal deposition was observed in the stroma and the tumor focally resembled translocation type (TFE3) RCC. Sarcomatous neoplastic cells were also seen. The cytoplasm of oncocytic and sarcomatous neoplastic cells was diffusely positive for anti-mitochondrial antibody and the ultrastructural examination detected many mitochondria in the cytoplasm of oncocytic carcinoma cells and sarcomatous neoplastic cells. The loss of chromosomes 1p, 2q11-22, 9 and 14 was observed using comparative genomic hybridization analysis. We thus report here a case of hitherto undescribed ACD-associated RCC intermingled with oncocytic cells, translocation type RCC-like area and sarcomatoid change. This is the sixth case of sarcomatoid RCC arising in end-stage kidney disease.