54 years old female with history of dermatomyositis, for which she is on immunosuppressive medication, presents with left lower quadrant abdominal pain. Blood tests reveal leucopenia and normal CRP.
CT images during portal venous phase after intravenous injection of contrast material show an oval area of fat attenuation surrounded by a ring of soft tissue adjacent to the descending colon. There is perifocal stranding of mesenteric fat and subtle thickening of the anterior visceral peritoneum.
Epiploic appendagitis (a.k.a. appendicitis epiploicae).
Epiploic appendages are small outpouchings of visceral peritoneum that contain fat and small blood vessels and arise from the serosal surface adjacent to the tenia coli in the colon. They are predominantly found in the left colon and cecum. An epiploic appendage may undergo torsion or occlusion of its central vessel. This results in inflammation and, eventually, acute ischemic infarction. Epiploic appendagitis is a rare and self limiting process, in which patients present with abdominal pain and rebound tenderness correlating with the location of the infarcted epiploic appendage. Its clinical manifestation may mimic that of acute appendicitis or diverticulitis, but laboratory findings are usually normal.
Typical CT features of epiploic appendagitis include demarcation of a fat containing area adjacent to colon that is surrounded by a ring of soft tissue. A central dot may be seen and represents a thrombosed vein or internal hemorrhage. Associated colonic wall thickening or other abnormalities are usually absent.
Kamaya et al.
Imaging Manifestations of Abdominal Fat Necrosis and Its Mimics
Radiographics (2011) 31(7):2021
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