Mucinous cystadenoma with calcification arising from renal pelvis radiologically resembled renal calculus with hydronephrosis: report of a rare case and review of the literature.

Primary mucinous cystic tumors occurring in the renal pelvis or the entire pyelocaliceal system are uncommon. Most are mucinous cystadenomas and less frequently mucinous cystadenocarcinomas. In fact, the publications on these neoplasms are limited to a few cases. Because mucinous cystadenomas of kidney are exceedingly rare, little is known about their natural history, pathogenesis and clinicopathologic features. Herein, we describe 1 case of mucinous cystadenoma arising from the renal pelvis with calcification, which resembled hydronephrosis with renal calculus radiologically. The patient presented with a history of intermittent dull pain on the right waist since 10 years ago. He had no history of removing urinary calculus or long-standing chronic infection in urinary system. The histopathology was unique since the inner surface of the cyst was covered by a mucinous epithelium connected to a urothelium, a transition from nonneoplastic urothelium to mucinous epithelium was demonstrated by immunohistochemical staining for GATA-binding protein 3 (GATA3). This suggests that mucinous cystadenoma of renal pelvis, like its malignant counterpart, maybe arises in foci of metaplastic mucinous areas.