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Although lipomas of the colon are considered the second most common benign nonepithelial tumors of the colon and rectum,^1- 8 they are rare. From July 17, 1997, until October 2004, we encountered 7 cases of lipomas of the colon. The patients ranged in age from 51 to 64 years (median age, 60 years) and included 3 men and 4 women. Their clinical presentation included rectal bleeding (n = 2), pain in the right iliac fossa (n = 3), pain in the left iliac fossa (n = 1), diffuse upper abdominal pain (n = 1), and symptoms and signs of intestinal obstruction (n = 1). Their diagnosis involved flexible sigmoidoscopy, colonoscopy, barium enema, computed tomography, and magnetic resonance imaging. Their management involved right hemicolectomy (n = 1), left hemicolectomy (n = 2), local excision (n = 2), and observation (n = 1).

In general, colonic lipomas are more common in women than men^5,8 and occur most often in the fifth and sixth decades of life.⁵ The incidence is estimated from 0.035% to as high as 4.4% in some series.⁵ Most lipomas are silent^8- 9 and often detected incidentally by colonoscopy⁹ or barium enema.⁴ The patients may have intussusceptions^2- 3,5- 6 as demonstrated by magnetic resonance imaging, change in bowel habits,^5- 6 or simple mechanical obstruction.⁵ Barium enemas are not diagnostic and can miss lipomas smaller than 2 cm⁸; however, they are mandatory to rule out malignant lesions. On barium study, lipomas are typically round or ovoid, sharply defined, smooth, filling defects.⁴ Colonoscopy, on the other hand, can readily show lipomas since most of them are submucosal.⁹ The lipomas typically appear as smooth, spherical, slightly yellowish polyps of variable size⁹ (0.5 to >5 cm) with either a broad base of attachment or a thick pedicle.⁹ The mucosa is usually normal; however, it may ulcerate.^2,9 Probing the polyp will give you the cushion sign^3,9 (pillow-like indentation), and grasping the overlying mucosa with biopsy forceps gives the tenting effect.⁹ Biopsy may result in an extrusion of yellow fat, the “naked fat” sign.^3,9 If a lipoma is removed, it will float in formalin fixative.⁹ Computed tomography can be used to identify lipomas of the colon easily by their homogeneity,^3- 4 and it can be used to easily differentiate between liposarcomas by showing absence of heterogeneity and areas of increased density.⁴ Liposarcomas of the colon are, however, extremely rare.⁸ Recently, computed tomography colonographic examination (virtual colonoscopy) has been performed to detect colonic lipomas.³

Seventy percent of colonic lipomas are localized in the right colon,^3,5- 7 followed by localization in the transverse colon and then the descending colon, an opposite distribution in comparison with adenocarcinoma and adenomatous polyps.⁷ Colonic lipomas are usually encapsulated submucosally^4,6,9 or are occasionally subserosal, and they can also be found in the ileum, duodenum, and jejunum (in decreasing order of frequency).¹ There are variable reports of incidents of multiple lipomas in the colon, the highest incidence being 7 of 20 cases.⁵

Perhaps the greatest clinical significance of lipomas lies in confusing them with adenomatous polyps or other serious pathological abnormalities.⁹ Theoretically, lipomas should be removed only if they cause symptoms⁸; however, there is no sure method short of excision for confirming the diagnosis.

The surgical management of lipomas is in the form of colotomy and enucleation or excision.⁸ Resection, however, is indicated in the presence of intussusception.⁸ Snaring of lipomas with a 1.5- to 3.0-cm diameter has been advised by Papp and Haubrich.¹⁰ On the other hand, Bar-Meir et al¹¹ described safe endoscopic removal of large 5-cm lipomas. The risk of perforation rises with broad-based polyps, and in a recent series,³ a 43% perforation rate was found. Surgical removal, preferably laparoscopically, has been advocated for lipomas larger than 2 cm in diameter.⁷ Endoscopic removal of small lipomas is generally safe but rarely indicated.^5,9

Correspondence: Nasser M. Amer, FRCS, 6 Windmill Close, Upminster, Essex RM14 2HD, England (nasser.amer@btinternet.com).

Accepted for Publication: June 13, 2005.