CT Appearances of Intraabdominal and Intrapelvic Fatty Lesions

CT Appearances of Intraabdominal and Intrapelvic Fatty Lesions

Luis Méndez-Uriburu¹, Jorge Ahualli, Julio Méndez-Uriburu, Martín Méndez-Uriburu, Luis Fajre, Federico Méndez-Uriburu and Ramón Carabajal

¹ All authors: Centro Radiológico "Luis Méndez Collado," Muñecas 444, San Miguel de Tucumán, Tucumán 4000, República Argentina.

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Fig. 1. —40-year-old woman with echogenic nodule that was detected on sonography and suspected of being hemangioma. CT scan reveals well-defined oval mass (arrow) with attenuation values of fatty tissue (–57 H) and consistent with angiomyolipoma, which was confirmed by percutaneous fine-needle biopsy.

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Fig. 2A. —71-year-old woman who presented with nonspecific abdominal pain. Contrast-enhanced CT scan incidentally reveals intrahepatic focal fatty lesion (–27 H) containing thin septa that was interpreted as hepatic angiomyolipoma.

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Fig. 2B. —71-year-old woman who presented with nonspecific abdominal pain. Contrast-enhanced CT scan obtained 2 years later shows no changes from previous scan (A). Fine-needle biopsy confirmed diagnosis of hepatic angiomyolipoma.

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Fig. 3. —45-year-old obese man with diabetes and pancreatic lipomatosis. Abdominal CT scan reveals pancreatic parenchyma has been completely replaced by fatty tissue with marked glandular atrophy. Note dense acini (arrows) separated by increased fatty tissue.

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Fig. 4. —42-year-old man with focal fatty infiltration of pancreas. Helical CT scan shows hypoattenuating pancreatic mass (arrow) that does not deform border and has typical fatty density (–40 H), indicating mass is composed of fat.

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Fig. 5. —71-year-old man with anemia. CT scan shows well-defined intragastric mass in pyloric segment. Mass has smooth margins (arrows) and attenuation of –99 H, consistent with gastric lipoma.

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Fig. 6. —57-year-old woman with bladder cancer. Contrast-enhanced CT scan reveals polypoid lesion extending through proximal duodenum (arrow), with typical fatty density (–43 H). Lesion is surrounded by air (arrowheads) and duodenal walls. Endoscopy confirmed transpyloric prolapse of gastric lipoma.

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Fig. 7A. —71-year-old man who presented with dyspepsia and vomiting. CT scan was obtained using oral but no IV contrast agent with patient in dorsal decubitus position. Fat-density mass (arrow) surrounded by air (arrowheads) and intestinal fluid is revealed and cystic mass (asterisk) is visible on outer margin of right kidney.

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Fig. 7B. —71-year-old man who presented with dyspepsia and vomiting. CT scan was obtained with patient in right lateral decubitus position after second administration of oral contrast agent and first administration of IV contrast agent. Intraduodenal fatty lesion (arrow), surrounded by second dose of oral contrast agent, can be clearly seen.

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Fig. 8. —65-year-old man with history of testicular tumor. CT scan shows incidentally found oval fatty lesion (arrow) in third section of duodenum in front of aorta and inferior vena cava. Lesion is of homogeneous fat density, consistent with duodenal lipoma.

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Fig. 9A. —71-year-old woman with abdominal colic. Oral contrast-enhanced CT scan reveals round intraluminal mass (arrow), characterized by fat-attenuation mass (tip of lipoma) and thin halo (arrowheads), which is suggestive of mesenteric fat resulting from intestinal intussusception.

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Fig. 9B. —71-year-old woman with abdominal colic. CT scan (2 cm caudal to A) shows lipoma (arrow) clearly as lead point in small-bowel intussusception.

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Fig. 9C. —71-year-old woman with abdominal colic. CT scan obtained with patient in right lateral decubitus position shows lesion (arrow) involves different layers of small intestine and highlights its homogeneous fat density.

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Fig. 10. —65-year-old woman with colonic lipoma. CT scan obtained with oral and IV contrast material shows colonic mass (arrow) on proximal part of transverse colon with density and characteristics identical to those of adipose tissue.

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Fig. 11. —67-year-old man with mesenteric panniculitis. Unenhanced abdominal CT scan shows discrete increase (arrowheads) in density of fatty tissue surrounding mesenteric vessels without displacement. Note thin halo of normal fatty tissue surrounding mesenteric vessels.

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Fig. 12. —71-year-old man with history of treated lymphoma and "misty mesentery." CT scan shows heterogeneous increase in fat surrounding mesentery root (arrows) results in thin peripheral capsule and mass effect on loops of adjacent small intestine (arrowheads).

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Fig. 13. —47-year-old woman with cavitating mesenteric lymph node syndrome. Helical CT scan obtained after administration of oral and IV contrast material shows multiple rounded fluid-attenuation (10 H) masses with thin walls (arrows) in mesentery. Some masses have lower attenuation values (–50 H) (arrowheads) indicating fatty material.

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Fig. 14. —33-year-old woman with adrenal myelolipoma. Helical CT scan obtained without IV contrast agent shows right adrenal mass (long arrow) with heterogeneous density in more dense central area (short arrow) and fatty density in peripheral area (–102 H).

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Fig. 15A. —41-year-old man who presented with adrenal myelolipoma. CT scan shows well-defined adrenal mass (arrow) characterized by low-attenuation tissue (–84 H) reflecting fat in myelolipoma, mixed with bone marrow elements.

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Fig. 15B. —41-year-old man who presented with adrenal myelolipoma. CT scan obtained 7 years after A shows persistent right adrenal lesion (arrow) with same appearance and size as in previous scan (A) but with slight increase in its density, probably because of higher content of hematopoietic tissue within it.

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Fig. 16. —71-year-old woman with occult blood in feces. Enhanced CT scan shows tumor (4-cm diameter) (arrow) on outer margin of right kidney with fatty density pattern (–81 H) and more dense lineal areas characteristic of renal angiomyolipoma.

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Fig. 17. —52-year-old woman with renal mass depicted on sonography. CT scan obtained with oral and IV contrast material shows typical fatty mass containing vessels and tissues located in front of left kidney (white arrow), with defect present in renal parenchyma (black arrow) that shows renal origin of lesion, thus differentiating renal angiomyolipoma from retroperitoneal liposarcoma.

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Fig. 18. —64-year-old woman with tuberous sclerosis and large bilateral renal angiomyolipomas. CT scan shows several lesions with fatty content (long arrows) generously projecting to perinephric space. Thus, serpentine vascular structures (short arrows) located within lesions can be clearly seen.

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Fig. 19A. —55-year-old woman with hemorrhagic renal angiomyolipoma. Helical CT scan obtained without contrast agent shows large heterogeneous tumor mass (white arrow) measuring about 8 cm, with fatty content and more dense areas suggestive of intratumoral hemorrhage (black arrow). Note discrete hyperdensity compared with adjacent muscular structures.

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Fig. 19B. —55-year-old woman with hemorrhagic renal angiomyolipoma. Contrast-enhanced helical CT scan shows that fatty lesion (white arrow) is associated with renal parenchyma, which is laterally displaced by lesion. Hemorrhage resulting from rupture of intratumoral aneurysm is more clearly seen in sloping region (black arrow).

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Fig. 20. —56-year-old woman with malignant melanoma. Contrast-enhanced CT scan of abdomen reveals lipoma (arrow) in left kidney resembling simple renal cyst but with completely homogeneous fatty density (–99 H). (Compare with density of intestinal air and subcutaneous fat.) Note absence of vessels and tissue within lesion, findings that differ from those of angiomyolipomas.

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Fig. 21. —71-year-old man with left renal sinus lipomatosis. CT scan shows highly increased fatty deposit in left renal sinus (arrow) that surrounds and compresses collecting system. Renal parenchyma thickness (arrowheads) is slightly reduced, and thin calcifications are seen in gallbladder.

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Fig. 22. —Replacement lipomatosis in 50-year-old woman with uterine cervix adenocarcinoma. CT scan obtained without IV contrast agent shows changes in right renal parenchyma associated with generous fatty infiltration (arrow) of both renal parenchyma and perinephric space. Renal pelvis shows calcific staghorn lithiasis (asterisk).

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Fig. 23A. —52-year-old woman with palpable mass in pelvis. CT scan obtained with patient in supine decubitus position reveals large tumor mass with two well-defined areas with different densities. Higher area (asterisk) has density of –90 H (slightly lower than adjacent fat), whereas sloping portion (arrow) has intermediate density ranging between that of fat and that of soft tissues. Compare density with that of psoas major. Presence of floating hairy mass is seen as wave on horizontal level.

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Fig. 23B. —52-year-old woman with palpable mass in pelvis. On CT scan obtained with patient in prone decubitus position, septa can be seen inside mass (arrow), with mobility of the fluid–fatty content due to presence of fatty tissues of different weights.

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Fig. 24. —47-year-old woman referred for suspected dermoid cyst. CT scan shows typical appearance of mature cystic teratoma (dermoid cyst), with components of three germinative layers consisting of low-density fatty tissue (straight arrow), teeth (curved arrow), and structures with attenuation similar to that of abdominal musculature (arrowheads).

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Fig. 25. —48-year-old woman with ovarian lipoma. Helical CT scan shows well-defined tumor in right adnexal region with smooth margins (arrow) and attenuation of –47 H. Surgery confirmed diagnosis.

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Fig. 26. —66-year-old man with hematuria. CT scan shows well-defined, homogeneous mass (arrow) with generous fatty content (–107 H) and discrete mass effect on loops of adjacent small intestine, which are characteristic of retroperitoneal lipoma. Absence of more dense areas within lesion allows differentiation from liposarcoma.

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Fig. 27. —57-year-old woman with retroperitoneal liposarcoma. CT scan obtained with oral and IV contrast materials shows huge retroperitoneal tumor mass (long arrows) with heterogeneous fatty density that has septa (short arrows) and well-defined lobulated contours. Mass effect on adjacent structures is evident, but no infiltration is seen. Left kidney is in contact with but is not infiltrated by tumor.

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