Mesenteric lipoma is a rare example of intraperitoneal lipoma. As they do not infiltrate the bowel lumen, most of these lesions are asymptomatic. However, increasing the size of the mass can lead to recurrent abdominal pain. They may present in the acute setting with intestinal obstruction owing to bowel volvulus, compression or even adhesion [6, 7]. As in our case, the patient had a classic triad of intestinal obstruction secondary to mesenteric lipoma. In fact, intestinal obstruction also can occur in intramural lipoma. In this rare circumstance, the patient will develop intestinal obstruction secondary to intussusception, in which the lead point will be the intramural lipoma .
A radiographic examination may help identify the mesenteric lipoma in the presence of the intestinal obstruction, likely due to the discrepancy of contrast in between air within the dilated bowels and lipoma, where the air is more radiolucent than fat [5, 8]. Nevertheless, an abdominal radiograph should continue to be the initial imaging investigation for suspected intestinal obstruction due to ease of accessibility and cheaper cost. It is highly sensitive in detecting intestinal obstruction, abnormally located air such as pneumoperitoneum or pneumatosis internalis, as well as obstructing intraluminal pathology such as foreign bodies [9, 10]. Radiographs are sensitive in detecting small bowel obstruction ranging from 59 to 93% . We were able to determine the small bowel obstruction in our case but unfortunately unable to determine the cause of obstruction.
Ultrasound abdomen is recommended by some writers as the primary imaging investigation, however with the risk of misinterpretation of a mesenteric lipoma as normal-appearing mesenteric fat and omental tissue . Most writers are attributing CT scan as the best diagnostic imaging modality which assists in diagnosing mesenteric lipoma [5, 13]. The differences of contrast between the lipoma and normal-appearing mesenteric fat due to radiographic attenuation discrepancy enable the radiologist to locate the lesion. This radiographic attenuation discrepancy is described as Hounsfield unit (HU) widely used in computed tomography images . Simple lipoma typically appears as a mass of homogenous adipose tissue with similar attenuation to subcutaneous fat between -80 and -120 HU. Unlike angiomyolipoma, these lesions are not contrast-enhancing . Complications caused by extraluminal tumours, such as volvulus, which would demonstrate the typical “vortex” pattern . Besides that, a CT scan enables further characterisation of the lesion, which may assist in the diagnosis of liposarcoma, where liposarcoma may demonstrate heterogeneity, adjacent structure infiltration and local aggressiveness . However, magnetic resonance imaging (MRI) plays a main role in differentiating benign from malignant lipomas, especially in a giant type . Another important differential is liposarcoma which appears less hypodense and has thicker septation . Other than that, MRI also has difficulties to differentiate between lipoma and mature teratoma that contains fatty components .
Surgical intervention is indicated with symptomatic or obstructed patients. There, however, is no consensus on the treatment of incidental fat attenuating intraperitoneal masses. Laparoscopic approach with resection is the preferred option especially among small lipoma and non-obstructed bowel as compared to the conventional open surgery for the bigger tumour with intestinal obstruction, as in our case . Radioimaging cannot conclusively rule out malignancy. In cases with multiple lesions, careful assessment of each lesion is vital. Lipomas generally display low malignant potential, and decisions for surgery should be thoroughly discussed with asymptomatic patients. Surgical intervention should aim for complete excision especially for larger lesions due to the risk of malignancy, besides preventing recurrence .
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