Renographic Demonstration of Desmoid Tumor-Ureteral Fistula

A 20-year-old woman with Gardner syndrome and intra-abdominal desmoid tumors presented with increasing abdominal pain. CT demonstrated a new area of central hypodensity in a presumed desmoid tumor, compressing the left ureter. Findings were suspicious for abscess or fistula to the ureter. Subsequent 99mTc-MAG3 renogram demonstrated persistent extraureteral radiotracer activity in the region of the tumor, confirming a desmoid tumor-ureteral fistula. Desmoid tumors are benign but locally aggressive fibrous neoplasms that can be sporadic or associated with familial adenomatous polyposis syndromes, specifically Gardner syndrome. Fistula formation to the ureter has been reported infrequently.