ABSTRACT

Colorectal lipoma is a rare and generally asymptomatic lesion of the colon. Symptoms emerge as the lipoma grows in size. We here describe our diagnosis and management of a case presenting with abdominal pain, rectal bleeding, and protruding rectal mass for 15 days. A soft mass which had prolapsed through the anus was observed on physical examination. Colonoscopy could not be performed due to the irreducible mass, and urgent surgery was planned. The mass was resected with rectosigmoid resection. The patient developed no complications and was discharged on the 7th postoperative day.

Introduction

Colorectal lipomas are rare benign mesenchimal tumours and are generally asymptomatic. They may cause abdominal pain, diarrhea, rectal bleeding, tenesmus, obstruction, nausea, vomiting, distension and prolapsus by becoming symptomatic due to enlargement.1 Clinical findings may overlap with malignant tumour.

Case Report

A 51-year-old female patient admitted to emergency service with complaints of rectal bleeding and a mass prolapsing through anus for 15 days. Her history did not reveal weight loss or loss of appetite. Patient did not have any known disease, history of drug use or undergone surgery; and no abnormality was detected on complete blood count and blood biochemistry. A soft, smooth, bright, erythematous, 5-6 cm sized mass which prolapsed through anal canal and occluded the lumen was detected in anal examination of patient with tenderness and little distension in abdominal examination (Figure 1). Urgent surgery was planned for patient because colonoscopy also couldn’t be performed due to unreductable mass. In operation table, it was observed with the help of rigid rectosigmoidoscopy that root of the lesion was located 20 cm from anal verge. It was concluded that endoscopic resection was not applicable; then laparotomy was performed. In laparotomy, invagination in sigmoid colon was observed (Figure 2). When colotomy was performed, a 7-8 cm sized soft mass was located at the distal part of sigmoid colon (Figure 3); then rectosigmoid resection was performed (Figure 4). After uneventful postoperative course, patient was discharged at postoperative 7^th day. Pathological examination was revealed a vascular lipoma with 8 cm in diameter in colon lumen. No recurrence has been occured during 4 years of follow-ups.

Discussion

Although colorectal lipomas are second most common benign colon tumors; rate of incidence in general population is very low. Its incidence ranges between 0.2% and 4.4%. It is more common among women aged between 50-70. Majority of them are located at right colon as well as caecum (most frequently).^1,2 Also, 10% of them may be multiple.³ Although 90% of them are located submucosally, they may also be located at subserosa or mixed localizations.⁴

Lipomas located at colon are generally asymptomatic and diagnosis is generally made by endoscopic procedures or incidentally during abdominal surgeries.⁵ Size of lipomas may range between 2 mm and 30 cm in diameter.⁶ Symptoms are correlated with size of lipoma. It was reported that lesions sized above 4 cm are more likely to be symptomatic whereas lipomas sized below 2 cm are generally asymptomatic and diagnosed incidentally.¹ Although symptoms may vary according to the localization of the lipoma; abdominal pain, hemorrhage, invagination,⁷ obstruction, nausea, vomiting, distention, perforation,⁸ prolapsus⁹ may occur.

Diagnosing lipoma with imaging modalities may be difficult. Its signs rarely appear in barium graphies. If specific signs of adipose tissue can be identified in magnetic resonance imaging and computerized tomography; differentiating lipoma from colon cancer or polyp may be possible.^4,10 Lipomas may be seen as soft, smooth, sessil or pedicled yellow lesions which appear as submucosal swelling without ulceration or lesion on mucosa. Mucosal pathology may not be seen and deceiving reports may arise due to their submucosal origin. Lipomas may overlap with polyps and tumours during colonoscopy and definitive diagnosis may only be made by pathology results after excision of lesion.¹¹

Different approaches like enucleation, local excision, colotomy and segmental resection may be chosen for treatment.² Regular follow-ups are suggested for asymptomatic lipomas incidentally detected which was sized below 2 cm whereas endoscopic excision is suggested for symptomatic lipomas.^2,5 Risk of perforation and bleeding during endoscopic excision is increased in lipomas sized above 2 cm in diameter. Therefore, segmental colectomy is preferable among other surgical methods.⁵ Transanal excision may be performed in distally localized masses. However; a case report related with excision of a 7 cm-sized colon lipoma after endoscopic submucosal dissection without complication is present in literature.¹² Groups preferred endoscopic submucosal excision even in large lipomas have suggested that other surgical methods must be chosen in cases of broad-based and sessile masses, suspicion of malignancy, presence of complications such as invagination or obstruction.¹²

In conclusion, colorectal polyps are especially symptomatic when they are sized above 4 cm in diameter by causing invagination, obstruction, prolapsus and rectal bleeding. A widely accepted algorhythm in treatment is not available; however, excision of symptomatic lesions sized above 2 cm in diameter has been suggested.