Figure 12a. Pseudomyxoma retroperitonei resulting from rupture of a mucinous cystadenocarcinoma of the appendix in a 64-year-old man. Contrast-enhanced CT scans show lobulated hypoattenuating masses in the right lower quadrant (arrows in a, thick arrows in b), mass effect on the right psoas muscle and right ureter, and a tiny wall calcification (thin arrow in b).