Upper Urinary Tract Adenocarcinoma Arising in Tubular Adenoma-A Rare Entity: Report of 2 Cases and Review of Literature.

Tubular adenoma of the urinary tract is a recently recognized entity, and there is a paucity of clinicopathological information. We describe 2 rare cases of adenocarcinoma of upper urinary tract arising in the background of tubular adenoma with high-grade dysplasia. The first case was an extremely uncommon combination of multifocal tubular adenomas involving ureter and renal pelvis and adenocarcinoma of kidney in a patient with renal calculi. The second case was of adenocarcinoma of kidney arising from tubular adenoma of renal pelvis in the right moiety of horseshoe kidney. There was no microsatellite instability. These findings indicate, probably, an adenoma-carcinoma pathway is also followed in the urinary tract similar to the gastrointestinal tract. To the best of our knowledge, no such observations are reported in the English literature previously.