Acquired cystic disease-associated renal cell carcinoma: a clinicopathological study of seven cases.

The disease entity of acquired cystic disease (ACD)-associated renal cell carcinoma (RCC) has been recently incorporated into the international renal tumor classification. However, there are a few descriptions on clinicopathologic features. We performed a clinicopathologic study of seven cases with ACD-RCC. All tumors were incidentally found. Histologically, the tumor consisted of microcystic or cribriform pattern of neoplastic cells with deeply eosinophilic to oncocytic cytoplasm in the stroma of oxalate crystal deposition. Three cases contained the area of sarcomatoid transformation, of which one case also demonstrated rhabdoid phenotype foci. Six among seven patients had a hemodialysis history of more than 10 years and two patients showing the dedifferentiation had a hemodialysis history of more than 20 years. The follow-up duration ranged from 18 to 107 months with a mean of 59.1 months. Regarding the outcome, four patients were alive without disease. One patient was alive with metastasis 10 months after the operation. No patient died of disease. Finally, ACD-RCC generally pursues a favorable clinical course, but tumors with a hemodialysis history of more than 20 years may cause the dedifferentiation such as sarcomatoid change or rhabdoid features and this phenomenon may lead to worse clinical outcome.