DIFFERENTIAL-DIAGNOSIS OF FAT-CONTAINING LESIONS WITH ABDOMINAL AND PELVIC CT

Recognition of fat within an organ or lesion on abdominal and pelvic c omputed tomographic scans is an important clue to guiding a differenti al diagnosis. A systematic approach to these lesions, including a pati ent's age and clinical history, along with the appearance and location of the lesion often allows a specific differential diagnosis. The ana tomic sites of origin for these lesions are the gastrointestinal tract , genitourinary system, and retroperitoneum. Some of the more common e ntities include various forms of fatty change in the liver, fibrofatty mesenteric proliferation in Crohn disease, ovarian dermoids, and hern iations of abdominal fat. In addition, pitfalls such as pathologic pro cesses engulfing normal fat (eg, perirenal abscess) and iatrogenic inc orporation of normal fat (eg, omental packing in liver lacerations) sh ould also be included in the differential diagnosis. Familiarity with certain benign occurrences, such as focal fat in the liver adjacent to the falciform ligament and lipomatous infiltration of the ileocecal v alve, obviates invasive diagnostic procedures.