Figure 3. Patient with unsuspected metastatic melanoma of the small bowel and colon, the colonic metastasis causing intussusception. A 60-year-old man with weight loss and abdominal pain. CT at the level of the pelvis shows a round, target-shaped mass in the left iliac fossa (arrow). It consists of a central hyperdense area (contrast medium in the lumen of the intussusceptum) and a thick soft tissue mass around it with two "half-moon" shaped hypodense areas representing intussuscepted mesenteric fat. A peripheral rim of contrast medium outlines the space between the opposing walls of the intussuscipiens and the intussusceptum (arrow). Another large soft tissue mass (m) is seen in the right iliac fossa around a distal small bowel loop. Both the distal ileum and part of the left colon were resected.