Large Descending Colon Lipoma Causing Intussusception and Mimicking Malignancy

Abstract

Presentation & History: A 69-year-old previously healthy male presented with a 1-month history of hematochezia and 10 lb wt loss. The patient denied any changes in bowel movement frequency; he continued to average 1–2 bowel movements per day. The patient denied abdominal pain, nausea or vomiting. Previous medical history included an appendectomy and hernia repair, ankle fracture. The patient took no medications, and denied any behavioral risk factors. Family history revealed a daughter with ulcerative colitis, and no colorectal cancer. Physical Exam & Laboratory Evaluation: Physical exam was unremarkable. The complete blood count and the basic metabolic panel were normal. CT revealed a mass in the descending colon with partial intussusception involving the sigmoid colon, suggestive of carcinoma. There was no adenopathy or evidence of metastases. Treatment & Hospital Course: Colonoscopy revealed a 7 cm, pedunculated, ulcerated, fungating mass with partial intussusception just distal to the splenic flexure at 70 centimeters from the anal verge. Biopsies only revealed inflammation.[figure1]A repeat colonoscopy was performed and the lesion was removed with a large snare and electrocautery. Pathology revealed a lipoma with no evidence of malignancy. The patient has done well thereafter.FigureDiscussion: This case is unusual for several reasons: First, colonic lipomas are comparatively rare, with a reported incidence less than 5%. Second, colonic lipomas are positively correlated with distance from the anus. Our patient's lipoma was found in the descending colon. Third, colonic lipomas are most frequently small and asymptomatic. Lipomas larger than 2 cm are more often symptomatic, potentially causing obstruction, bleeding, or– very rarely – intussusception. Our patient had both a symptomatic and intussuscepted lipoma. Fourth, grossly, lipomas are generally covered by smooth mucosa. Our examination revealed an ulcerated fungating mass that appeared grossly malignant. Large lipomas associated with intussusception are not easily differentiated from malignancies. Our experience shows that lipomas with unexpected gross appearance can also be easily mistaken for malignancy.