Obstructive Pyelonephritis Secondary to Ureteral Compression by an Intra-Abdominal Desmoid Tumor in Familial Adenomatous Polyposis: A Case Report.

In patients with familial adenomatous polyposis, intra-abdominal desmoid tumors should be recognized as a rare but important cause of ureteral obstruction and obstructive pyelonephritis. Prompt cross-sectional imaging, early recognition, and multidisciplinary management are essential for preserving renal function, treating infection, and preventing irreversible urinary tract complications.