73 Focal Decreased-Attenuation Masses in the Liver

CLINICAL IMAGAGINGAN ATLAS OF DIFFERENTIAL DAIGNOSIS

EISENBERG

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

• Fig GI 73-1 Simple hepatic cyst. A 20-cm fluid-filled mass in the right lobe of the liver displaces the abdominal contents and compresses the inferior vena cava. After aspiration and the instillation of alcohol, there was virtual ablation of the cyst.114

• Fig GI 73-2 Echinococcal cyst. Multiple large cysts filling a massively enlarged liver.

• Fig GI 73-3 Polycystic liver disease. Innumerable lucent lesions of various sizes in a markedly enlarged liver. The patient also had severe polycystic kidney disease.

• Fig GI 73-4 Caroli's disease. (A) CT scan shows fluid-filled cystic masses in the liver. (B) Cholangiogram shows the characteristic dilatation of intrahepatic ducts.

• Fig GI 73-5 Choledochal cyst. (A) Contrast CT shows a cystic mass (C) that is well demarcated due to the dilation of the distal portion of the common bile duct. (B) Coronal oblique reformatted image shows fusiform dilatation of the common bile duct (arrow). Note also the dilatation of the intrahepatic biliary tree (arrowhead).115

• Fig GI 73-6 Hepatic abscess. (A) Unenhanced scan shows a single low-density lesion with poorly defined margins at the periphery of the liver. (B) After infusion of contrast material, there is rim enhancement with the margins of the abscess seen as a white line (arrows) of higher density than the surrounding normal liver. (C) CT scan in another patient shows a large collection of gas in a pyogenic abscess in the lateral aspect of the right lobe of the liver.116

Fig GI 73-7 Pyogenic abscess. Large mass (A) in the right lobe of the liver that contains low-attenuation areas reflecting early liquefaction.117

• Fig GI 73-8 Amebic abscess. Well-circumscribed, fluid-attenuation mass (consistent with a simple cyst) in the posterior portion of the right lobe of the liver.102

• Fig GI 73-9 Fungal abscesses. Numerous low-density lesions in a massively enlarged liver representing multiple abscesses containing Candida albicans.98

• Fig GI 73-10 Hydatid disease. (A) Unilocular cyst of water attenuation with a ringlike pattern of calcification. (B) Multiple daughter cysts in their typical peripheral location within the mother cyst (arrows). There is partial calcification of the pericyst. (C) Dense circular area of increased attenuation within the cyst represents detached and collapsed parasitic membranes (arrows).118

• Fig GI 73-11 Echinococcal multilocularis. (A) Unenhanced and (B) contrast-enhanced scans demonstrate a large, irregular, hypoattenuating lesion with dense punctuate calcifications, which are more clearly seen on the unenhanced image. Note the poor enhancement of the lesion.119

• Fig GI 73-12 Schistosomiasis. Characteristic pericapsular and periportal calcifications, which give the liver a tortoise shell appearance.119

• Fig GI 73-13 Tuberculosis. Multiple low-attenuation areas of varying size in the liver and spleen. The imaging findings are not specific, and thus biopsy is required whenever this disease is suspected.119

• Fig GI 73-14 Fascioliasis. (A, B) Contrast scans show clustered small low-attenuating lesions with peripheral enhancement in the subcapsular area of the right hepatic lobe. Note the characteristic crooked tract-like lesion (burrow tract) in B (arrows).120

• Fig GI 73-15 Cavernous hemangioma. (A) Initial scan after a bolus injection of contrast material demonstrates a large low-density lesion in the posterior segment of the right lobe of the liver.121(B and C) Delayed scans show progressive enhancement of the lesion until it becomes nearly isodense with normal hepatic parenchyma.

• Fig GI 73-16 Adenoma. Large low-density mass in the liver. Note the area of higher density (arrows), which represents a blood clot, along the posterior aspect of the lesion.

• Fig GI 73-17 Focal nodular hyperplasia. Noncontrast scan shows an area of low attenuation (arrow) that is indistinguishable from a primary or secondary hepatic neoplasm. The lesion became isodense after the administration of contrast material.122

• Fig GI 73-18 Angiomyolipoma. Well-defined hepatic mass (arrow) with the attenuation of fat.123

• Fig GI 73-19 Infantile hepatic hemangioendothelioma. Multiple, rounded, hypodense masses throughout the liver. On a delayed postcontrast scan, all of the lesions became isodense to the surrounding liver.124

• Fig GI 73-20 Primary hepatocellular carcinoma. (A) Huge mass with an attenuation value slightly less than that of normal liver. The black arrows point to the hematoma (H)-normal liver interface. Of incidental note is a pancreatic pseudocyst (white arrow) in the lesser sac between the stomach (S) and the pancreas. (B) On a slightly lower scan, there is absence of the fat plane surrounding the head of the pancreas (P), indicating invasion of the pancreas by the tumor.

• Fig GI 73-21 Primary hepatocellular carcinoma. Multiple low-attenuation masses in the liver.

• Fig GI 73-22 Fibrolamellar carcinoma. Contrast-enhanced scan shows a solitary lobulated, low-attenuation mass in the lateral segment of the left lobe with punctate calcification and central stellate scar. Note the retroperitoneal metastasis.104

• Fig GI 73-23 Cholangiocarcinoma. Large, lobulated mass containing multiple, large, chunky, dense areas of calcification. Note the central areas of decreased attenuation corresponding to fibrosis.105

• Fig GI 73-24 Biliary cystadenoma. Nonenhanced scan shows a well-defined, ovoid, low-attenuation liver mass with multiple internal septations. Multiple calcifications (arrows) are seen along the wall and internal septa.96

• Fig GI 73-25 Angiosarcoma. Contrast-enhanced scan shows multiple low-attenuation lesions in a patient with previous exposure to Thorotrast.125

• Fig GI 73-26 Metastases. Multiple, low-density metastases with high-density centers.

• Fig GI 73-27 Metastases. Several large, low-density lesions filling much of the liver. Although these lesions simulate benign cysts, their walls are somewhat shaggy and irregular.

• Fig GI 73-28 Kaposi's sarcoma. Multiple, ill-defined peripheral portal liver nodules (arrows) in a patient with disseminated AIDS-related disease. Some of the nodules show hypoattenuation, whereas others show enhancement.123

• Fig GI 73-29 Lymphoma. Multiple nodules are scattered throughout the liver.126

• Fig GI 73-30 Subcapsular hematoma. Well-circumscribed elliptical area of low-attenuation density (arrows) in the periphery of the right lobe of the liver. The patient had sustained blunt trauma to the upper abdomen 2 weeks previously.

• Fig GI 73-31 Intrahepatic hematoma. The patient had sustained a gunshot wound of the liver that was not appreciated at the time of laparotomy. (A) CT scan shows the bullet fragment (arrowhead) in a mixed low- and high-density collection. The high-density area (arrow) represents clotted blood. (B) One week later, the hematoma is larger and of lower density.89

Fig GI 73-32 Hepatic laceration. CT scan after blunt trauma shows an irregular low-density plane (arrows) passing through the right lobe of the liver.89

Fig GI 73-33 Biloma. Multiple intrahepatic and extrahepatic low-attenuation lesions after traumatic rupture of the biliary tree and bile peritonitis.

• Fig GI 73-34 Radiation injury. Well-demarcated region of low attenuation corresponding to the treatment port (arrowheads).127

• Fig GI 73-35 Intrahepatic extension of pancreatic pseudocyst. The area of decreased attenuation in the region of the falciform ligament (white arrow) is seen in association with a pseudocyst in the body of the pancreas (black arrow).128

• Fig GI 73-36 Focal fatty infiltration. The absence of a mass effect is seen both by the lack of contour abnormality and by the unaffected course of a portal vein branch through the area of focal fatty infiltration (arrows). Note that the margins of the lesion are poorly defined in this patient.108

• Fig GI 73-37 Hepatic infarction. Well-demarcated, wedge-shaped non-enhancing lesion in the posterior right hepatic lobe with peripheral low-attenuation components (straight arrows). Peripheral low-attenuation regions (curved arrows) could represent focal accumulations of bile and necrotic liver. Note the presence of ascites.129

Fig GI 73-38 Choledochal cyst. Contrast-enhanced scan shows dilatation of intrahepatic bile ducts simulating multiple cystic masses.130

• Fig GI 73-39 Sarcoidosis. Multiple irregular nodules of variable size.131

• Fig GI 73-40 Amyloidosis. Contrast-enhanced scan shows low-attenuation area in the right lobe. Note that nondisplaced portal and hepatic vessels course through the low-attenuation mass, suggesting an infiltrative rather than neoplastic etiology.132