Clinicopathological analysis of two cases with pelvis villous adenoma and review of relevant literature.

Villous adenoma is a rare primary tumor of the urinary system, especially the bladder and kidneys. This study presents two cases of right pelvis villous adenoma, including that of a 61-year-old patient who had experienced hematuria for more than 1 year and was diagnosed with bladder and ureteral stones via B-ultrasound examination, and the other one involving a 65-year-old patient who was hospitalized for 6 days due to a right upper quadrant mass and diagnosed with right renal pelvis stones and hydrops via B-ultrasound examination. Both patients underwent nephrectomy, and their histological analysis demonstrated papillary projections covered by columnar cells and goblet cells. The first patient had a large amount of renal pelvis mucus accumulation with obvious microscopic intestinal metaplasia and mild-moderate nuclear atypia. Immunohistochemical studies revealed positive carcinoembryonic antigen and the caudal type homeobox 2 staining with varying degrees of cytokeratin (CK)-7 and CK20 expression in both patients. Recurrences or metastasis was not observed during the follow-up period of 3-4 years.