90 Fatty Lesions in the Abdomen and Pelvis on Computed Tomography

CLINICAL IMAGAGINGAN ATLAS OF DIFFERENTIAL DAIGNOSIS

EISENBERG

DR. Muhammad Bin Zulfiqar PGR-FCPS III SIMS/SHL

• Fig GI 90-1 Hepatic angiomyolipoma. Well-defined oval mass (arrow) with an attenuation value of fatty tissue (-57 H) in a woman with an echogenic nodule suggestive of hemangioma detected on ultrasound.199

• Fig GI 90-2 Focal fatty infiltration of the pancreas. Hypoattenuating pancreatic mass (arrow) that does not deform the border and has typical fatty density.199

• Fig GI 90-3 Lipoma of the pancreas. Large, homogeneous, fat-attenuation mass within the pancreatic head (arrows) with lateral displacement of the common bile duct (arrowhead).200

• Fig GI 90-4 Pancreatic lipomatosis. Complete replacement of the parenchyma by fatty tissue with marked glandular atrophy. Note the dense acini (arrows) separated by increased fatty tissue.199

• Fig GI 90-5 Fatty replacement of the pancreas. In a patient with cystic fibrosis, pancreatic tissue is virtually completely replaced by tissue with fat attenuation (arrowheads). Note the thin linear density of the main pancreatic duct.200

• Fig GI 90-6 Colonic lipoma. Characteristic fat-attenuation mass (arrow) in the proximal part of the transverse colon.199

• Fig GI 90-7 Epiploic appendagitis. Ovoid mass of fat attenuation (open arrow) anterior to the descending colon. The mass is surrounded by a hyperattenuating rim. A central high-attenuation dot was seen on images obtained superiorly (not shown). Note the moderate fat stranding (arrowhead) and the mild focal thickening of the adjacent colonic wall (solid arrow).200

• Fig GI 90-8 Intussusception led by a lipoma. (A) Small amount of mesenteric fat between the walls of the intussusceptum and the intussuscipiens (arrows). (B) More superior image shows a leading lipoma (arrowhead).200

• Fig GI 90-9 Mesenteric panniculitis. Discrete increase (arrowheads) in density of fatty tissue surrounding mesenteric vessels without evidence of vascular displacement. Note the thin halo of normal fatty tissue surrounding the mesenteric vessels.199

• Fig GI 90-10 Cavitating mesenteric lymph node syndrome. Multiple, round, fluid-attenuation masses with thin walls (arrows) in the mesentery. Some of the masses have lower attenuation values (arrowheads), indicating the presence of fatty material.199

• Fig GI 90-11 Omental infarction. Inhomogeneous, round, high-attenuation fatty mass in the greater omentum (arrows). The mass is anterior to the ascending colon and exerts mass effect on it. There is mild adjacent wall thickening (arrowhead).200

• Fig GI 90-12 Inguinal hernia. Well-defined fatty mass within the inferior aspect of the right inguinal canal (arrow), representing herniation of intra-abdominal fat.200

• Fig GI 90-13 Adrenal myelolipoma. Large, heterogeneous right adrenal mass (long arrow) with a more dense area in the center (short arrow) and fatty attenuation (-102 H) in the periphery.199

• Fig GI 90-14 Adrenal myelolipoma. (A) Well-defined mass with predominantly soft-tissue attenuation in the left adrenal gland. Note the nodule of fat attenuation (arrow). (B) In another patient, a contrast scan shows a heterogeneous mass (arrows) with fatty and enhancing soft-tissue components. The presence of fat permits a reliable diagnosis of a benign myelolipoma despite the soft-tissue elements.200

Fig GI 90-15 Adrenal adenoma. Low-attenuation mass in the left adrenal gland (arrow).200

• Fig GI 90-16 Renal angiomyolipoma. Heterogeneous mass in the lateral portion of the left kidney. The mass is predominantly of soft-tissue attenuation and resembles a renal cell carcinoma. However, the presence of focal areas of fat attenuation (arrows) permits confident diagnosis of an angiomyolipoma.200

• Fig GI 90-17 Bilateral renal angiomyolipomas. Bilateral low-attenuation masses (long arrows) projecting to the perinephric space in this patient with tuberous sclerosis. Note the serpentine vascular structures (short arrows) located within the lesions.199

• Fig GI 90-18 Renal lipoma. Mass of completely homogeneous fatty density on this contrast image. Note the absence of vessels and tissue within the lesion, which differentiates this appearance from angiomyolipoma.199

• Fig GI 90-19 Renal sinus lipomatosis. Extensive fatty deposition in the left renal sinus (arrow) that surrounds and compresses the collecting system. The thickness of the renal parenchyma is slightly reduced (arrowheads). Of incidental note are thin calcifications in the gallbladder.199

• Fig GI 90-20 Replacement lipomatosis. Generous fatty infiltration (arrow) of both the right renal parenchyma and perinephric space. Note the calcified staghorn calculus (*) in the renal pelvis.199

• Fig GI 90-21 Ovarian teratoma. Large mass containing components of the three germ layers. It consists of low-attenuation fatty tissue (straight arrow), teeth (curved arrow), and structures with attenuation similar to that of the abdominal musculature (arrowheads).199

• Fig GI 90-22 Ovarian lipoma. Well-defined tumor in the right adnexal region that has smooth margins (arrow) and the attenuation of fat.199

• Fig GI 90-23 Retroperitoneal liposarcoma. There is a huge tumor mass (long arrows) with heterogeneous fatty attenuation that has septa (short arrows) and well-defined lobular contours. There is mass effect on adjacent structures, such as the left kidney, but no evidence of infiltration.199

• Fig GI 90-24 Retroperitoneal liposarcoma. The coarse, thickened septa (arrow) in this heterogeneous, fat-attenuation mass are suggestive of a well-differentiated tumor.200