40 year old man with acute onset of intestinal obstruction. He had abdominal distension and constipation.
The large bowel shows several pedunculated cauliflower-like polyps. A portion of the bowel (intussusceptum) has telescoped into the immediately adjacent distal segment (intussuscipien). A polyp is found at the leading edge of the intussusceptum. Due to peristalsis, the mesentery has been pulled along leading to bowel obstruction, mesenteric lymphovascular compression, and infarction. Note dusky discoloration of the incarcerated portions, as well as the dilated proximal bowel.
The microscopy pictures show a tubular adenoma, which is the likely mechanical cause of the intussusception.