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Special Feature
December 1, 2007

Image of the Month—Diagnosis

Arch Surg. 2007;142(12):1222. doi:10.1001/archsurg.142.12.1222
Answer: Intussuscepted Transverse Colonic Lipoma

Lipomas of the intestine are relatively uncommon tumors of mesenchymal origin (Figure 2). They are most commonly found in the colon and cecum and only rarely reported in the stomach and esophagus.1Colonic lipomas were first described in 1757 by Bauer.2The incidence as reported in both clinical and large autopsy studies remains 2% to 4.4%.3In the colon, lipomas are mostly found on the right side (45%), with decreasing frequency heading toward the sigmoid colon. Thus, the distribution of lipomas is the exact opposite of colonic carcinoma. Most colon lipomas present as single pedunculated or sessile-appearing submucous lipomas. Less than 10% of reported lipomas are subserosal.4Most of these tumors are asymptomatic and occur largely as incidental findings during abdominal CT, colonoscopy, or laparotomy. Less than 25% of all patients with colonic lipomas develop symptoms. Symptomatic lipomas are usually found when the tumor grows to greater than 2 cm in diameter, leading to abdominal pain, hematochezia, change in bowel habits, or melena. Occasionally, patients may even experience defecation of lumps of hemorrhagic tissues due to self-amputation of the lipoma.5Colonic intussusception due to lipomas is unusual and often attributed to a malignant mass or a more common benign tumor. Buetow et al6report that lipomas must be at least 5 cm to cause colonic intussusception. However, masses as small as 3½ cm have also been reported to cause intussusception.7

Figure 2.
A 4-cm ulcerated submucosal lipoma in the resected ascending colon.

A 4-cm ulcerated submucosal lipoma in the resected ascending colon.

Given the age of the patient and symptoms on presentation, accurate preoperative diagnosis is difficult to attain. Barium enema studies typically reveal a radiolucent spherical filling defect with well-defined margins. The well-described squeeze sign, whereby changes in the shape of the lipoma can be detected through palpation, peristalsis, or patient position, may also be detected. Colonoscopy often detects the surface of a lipoma as normal and smooth. The typical colonoscopic features include the cushion sign or pillow sign, where pressing of the forceps against the lesion results in a depression or pillowing of the mass. A naked fat sign may also be detected with fat protruding at the biopsy site. Biopsies are usually not recommended for patients with lipomas because the lesion is beneath the normal surface mucosa and cannot promote diagnosis and a biopsy can increase the risk of bleeding and perforation. Abdominal CT scans are considered to be the most definitive diagnostic measure of recognizing colonic lipomas. The CT scans often detect lipomas as ovoid or pear shaped, with sharp margins and absorption densities typical of fatty compositions.

Treatment of colonic lipomas largely depends on size and symptoms. Patients with small asymptomatic colon lipomas simply require close, regular follow-up without any other intervention. Symptomatic lipomas require resection, especially those greater than 2 cm. The current indications for endoscopic resection are still controversial, and definitive guidelines are not available. Many have reported that risk of perforation or hemorrhage is increased with endoscopic resection, especially in sessile or broad-based lesions.8Surgical resection remains the preferred mode of treatment, especially when malignancy cannot be ruled out. Segmental colon resection is recommended for the removal of the lipoma. Good preoperative diagnosis, however, may help to limit the extent of surgical resection.

Correspondence:Michael E. Zenilman, MD, Department of Surgery, SUNY Downstate Medical Center, Box 40, 450 Clarkson Ave, Brooklyn, NY 11203 (mzenilman@downstate.edu).

Accepted for Publication: December 21, 2007.

Author Contributions:Study concept and design: Du. Acquisition of data: Du and Shah. Analysis and interpretation of data: Du, Shah, and Zenilman. Drafting of the manuscript: Du and Shah. Critical revision of the manuscript for important intellectual content: Du and Zenilman. Administrative, technical, and material support: Du, Shah, and Zenilman. Study supervision: Zenilman.

Financial Disclosure:None reported.

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