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Aberrant papillae and other filling defects of the renal pelvis.

A lucent filling defect within the renal pelvis or infundibulum seen during intravenous or retrograde urography presents a well known diagnostic problem for the roentgenologist. Although many lesions may produce a similar appearance on the initial study, several suggestions are offered here to help narrow the differential diagnosis.A combination of repeated urographies, oblique projections, occasional angiography, and careful attention to roentgenographic appearance immediately adjacent to the apparent filling defect will suggest the correct diagnosis in many cases.The cases illustrated and discussed include: the aberrant papilla; multiple papillae draining into a single calyx; a normal papilla with a short minor calyx draining into an infundibulum (seen en face); nonopaque calculus; blood clot; nonobstructing transitional cell carcinoma; cavernous hemangioma; a crossing vessel that impresses only one edge of the pelvis; and a pseudodefect produced by overlap of 2 or more adjacent infundibula.