Cytology of cystic nephroma: a case report

BACKGROUND: Cystic nephroma is a rare benign multiloculated cystic renal neoplasm that is often confused with multicystic renal cell carcinoma radiographically and cytologically. CASE: A 58-year-old woman was incidentally found to have a multiloculated cystic right renal lesion. Cytologic examination of the fluid aspirated from the lesion was reported as highly suspicious for renal cell carcinoma, but a right nephrectomy revealed a cystic nephroma. CONCLUSION: Cystic nephroma fluid is characterized by the presence of sparse epithelial cells with moderate nuclear atypia. Conversely, the fluid of multicystic renal cell carcinoma is moderately cellular with no or mild nuclear atypia.