Lobulated colonic lipoma mimicking carcinoma with intermittent intussusception

Lipomas are the most common nonepithelial tumors of the colon, and rank third in frequency among benign colonic tumors after hyperplastic and adenomatous polyps [1]. Symptomatic colonic lipomas are uncommon, accounting for 6 % in clinical series at the Mayo Clinic [2]. Intussuscepted colonic lipomas are rare and often confused with malignant tumors, so that most of them are diagnosed after intervention [3]. We report on a lobulated colonic lipoma with unusual presentations that mimicked carcinoma.

A 47-year-old woman presented with intermittent, colicky abdominal pain. Physical examination showed no specific finding except for pale conjunctiva. Laboratory investigation revealed iron-deficiency anemia. The fecal occult blood test was positive. Double contrast colon series showed an irregular lobulated mass, measuring 5 cm in diameter and located in the hepatic flexure ([Figure 1]). Colonoscopy revealed a 5 cm diameter polypoid mass with an irregular lobulated margin, tan-pink ulcerated surface, and easy contact bleeding in the ascending colon near the hepatic flexure ([Figure 2]). Abdominal computed tomography (CT) showed an intussuscepted lesion located in the hepatic flexure. An ill-defined fat-containing soft-tissue mass was measured at 5 cm in diameter and acted as a leading point of intussusception ([Figure 3]). Because of suspicion of malignant tumor, the patient underwent laparotomy with right hemicolectomy.

Figure 1 Double contrast colon series showed an irregular lobulated mass measuring 5 cm in diameter, located in the hepatic flexure.

Figure 2 Colonoscopy revealed a polypoid mass with an irregular lobulated margin, and tan-pink ulcerated necrotic surface that mimicked a malignant tumor.

Figure 3 Abdominal computed tomography showed an ill-defined fat-containing soft-tissue mass, which acted as a leading point of intussusception (a, arrow). The wall of the colon near the mass was thickened with rings of intussusception (b, arrow). There was no lymphadenopathy.

The gross appearance of the lesion was that of a polypoid hard mass measuring 5 × 4 × 4 cm, with an ulcerated necrotic surface and located at the distal ascending colon ([Figure 4]). The histologic findings revealed a lipoma composed of mature adipose tissue. The surface of the mass was superficially ulcerated with inflammation and fibrosis ([Figure 5]). The patient was discharged on the seventh day after the operation, following an uneventful recovery.

Figure 4 Resected specimen of the colon showed a polypoid hard mass measuring 5 × 4 × 4 cm, with an ulcerated necrotic surface, located at the distal ascending colon.

Figure 5 Pathologic findings revealed mucosal ulceration with inflammation and fibrosis. The submucosal mass was composed of mature adipose tissue. (Hematoxylin and eosin, original magnification × 100).

Large colonic lipomas (> 2 cm) can present as abdominal pain from obstruction or intussusception, and bleeding or chronic anemia could occur when mucosa overlying the lipoma is ulcerated [4]. Ulcerative and lobulated appearance may be due to fibrosis and healing of traumatic mucosa resulting from chronic and occasional intussusception [5]. In this case, abdominal CT is sensitive for colonic lipomas with intussusception.

Endoscopy_UCTN_Code_CCL_1AD_2AB

Endoscopy_UCTN_Code_CCL_1AD_2AC

References

• 1 Siegal A, Witz M. Gastrointestinal lipoma and malignancies.  J Surg Oncol. 1991;  47 170-174
• 2 Taylor B, Wolff B. Report of two unusual cases and review of Mayo Clinic experiences, 1976 – 1985.  Dis Colon Rectum. 1987;  30 888-893
• 3 Huh K C, Lee T H, Kim S M. et al . Intussuscepted sigmoid colonic lipoma mimicking carcinoma.  Dig Dis Sci. 2006;  51 791-779
• 4 EI-Khalil T, Mourad F H, Uthman S. Sigmoid lipoma mimicking carcinoma: case report with review of diagnosis and management.  Gastrointest Endosc. 2000;  51 495-496
• 5 Meghoo C AL, Cook P R, McDonough C A. et al . Large colonic lipoma with mucosal ulceration mimicking carcinoma.  Gastrointest Endosc. 2003;  58 468-470