Giant submucosal sigmoid colon lipoma.

A 67-year-old asymptomatic man presented for a screening colonoscopy. At colonoscopy (Olympus PCF-160AL video colonoscope) a polyp measuring 3 cm in diameter was identified in the sigmoid colon. A large vessel was visually identified within the stalk of this lesion. The polyp was submucosal and had a yellowish hue to it. The decision was made to remove this endoscopically. A snare was passed over the polyp and then an Olympus quick clip was placed below the snare (Fig. 1). The snare was tightened and the electrocoagulation unit was used to remove the polyp. There was no bleeding from the polypectomy site and the patient tolerated the procedure without any sequelae. Lipomas of the colon are rare. These submucosal lesions found at colonoscopy may attain substantial size of up to several centimeters in diameter. They commonly occur in the right colon and more often in women. Although the majority remain asymptomatic, colonic lipomas may present with symptoms such as pain, diarrhea, obstruction, and bleeding, and may be the lead point for intussusception. Size ( 2 cm) appears to correlate with symptomatology. Once detected, they are often observed in the absence of symptoms. They may warrant removal, however, to exclude confusion with other lesions that have a malignant potential. The decision to remove them and how best to do this, either endoscopically or surgically, remains controversial. Lipomas of the colon are benign tumors. Giant lipomas of the colon may be misinterpreted as a premalignant, adenomatous polyp, especially when arising in the left colon. In one series among 509 patients reported with neoplasms of the small and large bowel, there were four cases of lipomas found. Of these, one was located in the left colon and the remainder were in the ileocecum [1]. This represents an incidence of 0.7%; other authors have reported an incidence of 0.2% to 1.3% [1]. A lipoma of less than 2 cm is usually asymptomatic, whereas 75% of patients with a lesion larger than 4 cm have symptoms [1]. Giant lipomas of the colon are even less common; they may cause symptoms and therefore removal should be considered. Intermittent subacute obstruction of the colon has been described in the literature of very large colonic lipomas and may require surgical resection [2]. Intussusception has also occurred as a result of a giant lipoma of the colon [3], as has bleeding from the ulcerated tip of this lesion [4]. Colonic lipomas may be confused with malignant tumor at barium enema because of the presence of a filling defect; the diagnosis by this method is definitive in less than 20% of cases [1]. This diagnosis may be confirmed at colonscopy where the polyp will have the characteristic appearance of not involving the mucosa of the colon. The characteristic findings include the mucosa being elevated over the lipoma with the biopsy forceps (tent sign), indentation of the lipoma with the biopsy forceps (cushion sign), or the “naked fat sign” where the fat can be extruded after biopsy (Fig. 2) [4]. The greatest clinical significance of lipomas lies in their potential to be confused with adenomatous polyps or other aggressive pathology [4]. Endoscopic removal of lipomas may be associated with increased morbidity compared with retrieving adenomatous polyps. In the series by Pfell et al [4], 3 of 7 patients had a subsequent perforation after endoscopic removal of colonic lipomas. Fatty tissue does not conduct electricity well and soon it becomes impossible to bring the snare through the base [5]. Increasing the power to assist the completion of the polypectomy leads to increased heat production and damage to the adjacent bowel wall with subsequent perforation [5]. As noted by Chase and Yarze [6], lipomatous tissue contains a lower water content and therefore conducts electrosurgical current less efficiently. Tamura et al [7] have suggested that lipomas greater than 20 mm in diameter should be resected surgically, and believe that endoscopic removal of large lipomas remains a subject of controversy. They also advocate utilizing magnifying videoscopy and endoscopic ultrasonography to aid in diagnosis. A detailed endoscopic examination of the base of the lesion is necessary to decide * Corresponding author. Tel.: 1-314-577-8619; fax: 1-314-5778635. E-mail address: bahadua@slu.edu The American Journal of Surgery 186 (2003) 81~82