A cystic nephroma, also known as multilocular cystic nephroma, mixed epithelial stromal tumour (MEST) and renal epithelial stromal tumour (REST), is a type of rare benign kidney tumour.
Cystic nephromas are often asymptomatic.

Cystic nephromas are diagnosed by biopsy or excision. It is important to correctly diagnose them as, radiologically, they may mimic the appearance of a renal cell carcinoma that is cystic.

Differential diagnosis

• cystic partially differentiated nephroblastoma
• cystic standard nephroblastoma (cystic Wilm's tumor)
• cystic mesoblastic nephroma
• cystic renal cell carcinoma
• other renal cysts