Discussion

Lipomas are the most common soft tissue tumours of adipocytes. They are commonly located in proximal extremities and the trunk (1). Among all small bowel lipomas, mesenteric location accounted for only 4.8% of all cases (1).
It usually occurs in adults in the fourth to sixth decades of life (2). They are rarer in children and young people as in the case of our patient (1,3). There is an increased incidence of lipomas in patients with obesity ,diabetes mellitus, hypercholesterolemia, genetic predisposition and radiation therapy (3,4).However, our patient was thin and none of these factors was found in.
Mesenteric lipomas have generally a slow growth without invasion of surrounding organs (5). Besides, due to their soft consistency, most patients are asymptomatic with a chance discovery during abdominal laparotomy or CT scan done for other indications (1,6). The onset of symptoms depends on the size, rapidity of growth, and location of the tumor (1). An acute abdomen can reveal lipomas as they can lead to intestinal obstruction or volvulus(1,5). Less frequently, they can be revealed by chronic abdominal pain as in the case of our patient.
As the first-line investigation tool for abdominal pain due to its low cost, ultrasound shows homogenous or heterogenous well-limited and encapsulated intraperitoneal mass which may be confused with the mesenteric fat (1,7). Computed tomography (CT) scan of the abdomen is the gold standard imaging technique and plays a crucial role in the diagnosis of mesenteric lipoma (1). It allows the analyse of the nature and the density of the lesion, its exact location, its size and its extent. It typically shows an intraperitoneal and encapsulated mass with fatty attenuation with no lobulations, septations, or cystic organization (1,8). Mesenteric lipomas are often located in the ileal mesentery as in our case (1) .The first differential diagnosis to be suspected are liposarcomas. They are heterogeneous and contain thick septa with tumor extension to adjacent organs (9). Other rare differential diagnoses should be suggested, in particular lipoblastoma, cystic lymphangioma, lymphangiolipoma and neuroblastoma, but their radiological aspects are different from those of lipomas (5).
Magnetic resonance imaging (MRI) is also very performant to describe in detail the characteristics of the mass. She shows a hypointensity on T1-weighted and T2-weighted images without modification of the signal after injection of gadolinium (1). It confirms the fatty nature of the tumor and differentiates giant lipomas from well-differentiated liposarcomas (2). It prevents from doing invasive diagnostic techniques such as biopsy before surgery (2).
Therapeutic management of mesenteric lipoma is not consensual and it is based on the experience of the different teams. A small lipoma in a asymptomatic patient can be left in place (1). In the absence of signs of malignancy , complete surgical resection with, or if possible without, the affected intestinal loop is the treatment of choice due to the risk of intestinal obstruction by compression or volvulus (1,5). Laparotomy was the most used management strategy often with resection of the involved bowel followed by end-to-end anastomosis (1). Laparoscopy may be indicated particularly in cases of small lipoma with a clear plane of cleavage between the tumor and the adjacent small intestine, thus allowing enucleation of the mass (2). In our case, CT scan showed a typical benign mesenteric lipoma. Therefore, after an exploratory laparotomy, we performed a complete resection of the mass while conserving the intestine.
The recurrence rate of all lipomas after surgery is less than 5%, and is usually due to incomplete excision (6).