Intraperitoneal focal fat infarction: the great mimicker in the acute setting

The term intraperitoneal focal fat infarction (IFFI) includes various self-limiting clinical conditions that are caused by focal fatty tissue necrosis. Most of the cases of IFFI concern torsion or infarction of the greater omentum or the epiploic appendages. However, although rarely, perigastric ligaments can also undergo torsion also leading to fat infarction. IFFI clinically may mimic other pathologies, such as acute appendicitis or diverticulitis, making their clinical diagnosis a challenge. Ultrasound (US) and computed tomography (CT) have a high sensitivity and specificity for the diagnosis of IFFI excluding other pathologies, and in most cases, the clinical evolution is spontaneously favorable, thus helping to reduce the need for unnecessary surgical intervention. We review cases with IFFI in order to identify specific involvement patterns. Cases of epiploic appendages reported to an acute, subacute, and more chronic phase in order to present the self-limiting nature of this entity and the resultant absorption. We also present cases with falciform ligament infarction, as well as primary ("whirl sign" on CT due to greater omentum torsion) and secondary omental infarctions. The aim of this pictorial review is not only to extensively explore the imaging findings of IFFI but to also describe the clinical presentation and pathophysiology of the prementioned conditions.