Figure 14a. UPJO in a 49-year-old patient. The presence of a soft tissue mass in the renal pelvis was suggested at retrograde pyelography. (a) Coronal volume-rendered view shows three right renal arteries (arrows). (b) Coronal MPR image shows a curved UPJO (long arrow) above the level of the variant lower-pole renal artery (short arrow). Arrowhead = soft tissue mass in the superior renal pelvis. (c) Oblique coronal hilar clock-face view shows a dilated extrarenal pelvis (black arrowhead) ballooning anteriorly over lower-pole variant vessels (short arrow). Note that the transition zone of the UPJO is above the level of the variant vasculature (long arrow). White arrowhead = soft tissue mass in the superior renal pelvis. Right nephrectomy revealed a low-grade papillary carcinoma.