16 - Gastrointestinal Lipomas: Computed Tomography

Abstract

The occurrence of lipomas in the gastrointestinal tract is uncommon. Reliable radiographic diagnosis of this benign neoplastic lesion and precise differentiation from other intestinal malignant tumors are important to avoid unnecessary surgery. This chapter discusses current imaging methods for gastrointestinal lipomas, particularly computed tomography (CT). To diagnose intestinal lipomas, CT is considered the imaging modality of choice. Because CT permits accurate differentiation between fat and other tissues, an intestinal lipoma can be definitively diagnosed using CT. For an optimal characterization of intestinal lipomas using CT, oral and intravenous iodinated contrast administration is recommended. A positive oral contrast agent increases the contrast between the fatty tumor and the intraluminal surrounding. For patients undergoing CT examination for a suspected lipoma of the sigmoid, additional administration of rectal contrast agent is recommended. The findings on CT are characterized by a homogeneous mass with absorption densities ranging between −80 and −120 Hounsfield Units. These tumors are associated with ulceration of the mucosa and the presence of basilar strands of nonfatty elements correlated histologically with prominent fibrovascular septa. Other imaging methods in diagnosing gastrointestinal lipomas include magnetic resonance imaging (MRI), barium contrast studies, and endoscopy. Gastrointestinal lipomas have no malignant potential, and therefore surgery is only indicated in symptomatic patients or in lesions in which malignancy cannot be excluded. Patients with a submucosal mass detected on an endoscopic or upper gastrointestinal examination should undergo an abdominal CT examination since CT can specifically diagnose a lipoma.