[Intestinal occlusion due to a colonic lipoma. Apropos 2 cases]

Lipomas occur through the intestinal tract, from the hypopharynx to the rectum, the colon having the highest incidence, where lipomata are the commonest benign neoplasm after adenomata. Nevertheless they are uncommon. CASE REPORT. 1) A 68-year-old man presented as an emergency with abdominal pain associated with bowel obstruction. He had a 2 to 3 month history of intermittent right-sided abdominal pain, constipation spontaneously resolved. At laparotomy there was a mass of the transverse colon, next hepatic flexure. A right hemicolectomy was performed. The patient made an uneventful recovery. Histologic examination showed a lipoma of the submucosal plane. 2) A 65-year-old man presented as an emergency with lower abdominal pain associated with a prolapsed rectal polyp. He had 1 month history of passing fresh blood per rectum. Ap ast colonoscopy revealed a large polypoid lesion in the descending colon. Transanal examination revealed a polypoid lesion with a maximum diameter of 4 cm, acting as an intussuseptum. Transanal polypectomy was performed. At laparotomy there was an intussuseptum of the descending colon into the rectum: a left hemicolectomy was performed. Histology showed the polyp to be a submucosal lipoma. DISCUSSION. Lipomas are the most common benign nonepithelial tumors of the colon. Lipomata of the large bowel are reported as incidental findings in 0.3-0.5% of cases in large series of autopsies. In the wall of the intestine most lie in the submucosal plane, less frequently they are found in the subserosal plane. The commonest site for symptomatic solitary large bowel lipoma is the ascending colon, including the caecum, followed by the transverse colon, including both hepatic and splenic flexure, descending colon, sigmoid colon and rectum. The peak incidence for lipomata of the large bowel is in fifth-sixth decade. Colonic lipomas are generally asymptomatic but occasionally patients may have intermittent crampy abdominal pain secondary to intussusception of a pedunculated lipoma or with intermittent fresh rectal bleeding. On barium enema lipomas appear circular, ovoid, well demarcated, and smooth. A barium enema showing a relatively radiolucent mass, caused by the radiolucency of fat, is suggestive of a lipoma. The water enema, with water as the contrast agent, accentuates the difference in density between a lipoma and surrounding tissues. Another characteristic feature of lipomas on barium enema is said to be their fluctuation in size and shape during the study: "squeeze sign". Lipomas of the large bowel can be seen, however, by colonoscopy. On computerized tomography scan the lipoma has a uniform appearance and density. In expert hands pedunculated and sessile lesions can be removed endoscopically, but often large bowel lipomata are treated on the basis of a presumptive malignant diagnosis with exploratory laparotomy. CONCLUSION. Colonic lipomas, although unusual, continue to present difficulties in the preoperative differentiation between malignant and benign colonic neoplasm. Two cases of colonic lipomas are reported.