Filling Defects (masses)

Masses projecting into or occurring with the small intestine appear as filling defects on fluoroscopic studies. These filling defects may represent intraluminal, mucosal, intramural, or extrinsic masses. It can be difficult to distinguish the origin of a mass based on its fluoroscopic appearance, and CT is often a necessary adjunct to more clearly delineate the extent of the lesion.

Some clues can be obtained, however, from fluoroscopy that can aid in determining the location of the mass.  The most important aspect is the angle that the margins of the mass make with the intestinal wall.  Extrinsic or intramural masses will form obtuse margin angles, while mucosal masses will form acute angles.  Pedunculated masses will appear (surprisingly) pedunculated, and intraluminal masses will be filling defects completely surrounded by barium.

Most solitary filling defects are neoplastic (benign or malignant), with 75% of symptomatic masses representing malignancy. “Bull’s-eye” or “target” lesions are filling defects that contain a central area of barium collection.  This appearance denotes ulceration and is often (but not always) associated with malignancy.