Cystic nephroma: a diagnostic dilemma.

Cystic nephroma (CN) is a rare benign neoplasm of kidney with excellent prognosis. An accurate pre-operative diagnosis differentiating CN from other cystic renal malignancies may be impossible by clinical and radiological examination, and histopathological examination provides the final diagnosis. This report describes two adult patients with large multi-locular cystic renal masses on imaging and the diagnosis of CN was clinched post-operatively by the honeycomb appearance of the cut specimen and the finding of multiple, non-communicating fluid filled cysts lined by cuboidal or flattened epithelial cells and absence of blastemal cells on microscopy. Tumor diameter on cross sectional imaging remains the key parameter for treatment decisions in renal neoplasms, with nephrectomy being preferred for larger lesions.