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Arch Surg. 2006;141:834.

Answer: Intussusception Caused by Lipoma of the Colon
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}

AUTHOR INFORMATION

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

Accepted for Publication: June 13, 2005.

REFERENCES

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1. Megibow AJ, Redmond PE, Bosniak MA, Horowitz L. Diagnosis of gastrointestinal lipomas by CT. AJR Am J Roentgenol. 1979;133:743-745. ISI | PUBMED 2. Buetow PC, Buck JL, Carr NJ, Pantongrag-Brown L, Ros PR, Cruess DF. Intussuscepted colonic lipomas: loss of fat attenuation on CT with pathologic correlation in 10 cases. Abdom Imaging. 1996;21:153-156. FULL TEXT | ISI | PUBMED 3. Chiba T, Suzuki S, Sato M, et al. A case of a lipoma in the colon complicated by intussusception. Eur J Gastroenterol Hepatol. 2002;14:701-702. FULL TEXT | ISI | PUBMED 4. Kakitsubata Y, Kakitsubata S, Nagatomo H, Mitsuo H, Yamada H, Watanabe K. CT manifestations of lipomas of the small intestine and colon. Clin Imaging. 1993;17:179-182. FULL TEXT | ISI | PUBMED 5. Haller JD, Roberts TW. Lipomas of the colon: a clinicopathologic study of 20 cases. Surgery. 1964;55:773-781. ISI | PUBMED 6. Younathan CM, Ros PR, Burton SS. MR imaging of colonic lipoma. J Comput Assist Tomogr. 1991;15:492-494. ISI | PUBMED 7. Cossavella D, Clerico G, Rosato L, et al. Lipoma of the colon as an unusual cause of recurring partial intestinal occlusion: clinical case and review of the literature [in Italian]. Minerva Chir. 1998;53:277-280. PUBMED 8. Castro EB, Stearns MW. Lipoma of the large intestine: a review of 45 cases. Dis Colon Rectum. 1972;15:441-444. ISI | PUBMED 9. Pfeil SA, Weaver MG, Abdul-Karim FW, Yang P. Colonic lipomas: outcome of endoscopic removal. Gastrointest Endosc. 1990;36:435-438. ISI | PUBMED 10. Papp JP, Haubrich WS. Endoscopic removal of colonic lipomas. Gastrointest Endosc. 1973;20:66-67. ISI | PUBMED 11. Bar-Meir S, Halla A, Baratz M. Endoscopic removal of colonic lipoma. Endoscopy. 1981;13:135-136. ISI | PUBMED

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