RADIOLOGY: HEPATOBILIARY: Case# 78: HEPATIC ABSCESS-. Eighty-three year old woman presenting to the emergency room today with right upper quadrant tenderness, elevated liver function tests and elevated white blood cells. She is status post cholecystectomy. There is a large well-circumscribed mass with its epicenter in the medial segment of the left hepatic lobe containing an air fluid level, but mostly fluid-filled. There is patchy attenuation throughout the left hepatic lobe. Smaller areas of low attenuation with enhancing rims are identified adjacent to the largest collection, these are also mainly located in the medial segment of the left hepatic lobe and the anterior segment of the right hepatic lobe. There is no perihepatic fluid or ascites. The portal vein appears patent. There may be a mild amount of biliary ductal dilatation. A characteristic CT feature of most hepatic abscesses is a peripheral rim or capsule that enhances following contrast administration. Most abscesses have sharp, irregular external margins. Internal septations are common. Extrahepatic inflammatory changes may be present. Abscesses may be multiple but there is usually a dominant lesion larger than the rest. Gas bubbles indicate the presence of a gas-forming organism. An air-fluid or fluid-debris level may be seen. A large air-fluid collection may indicate communication with the GI tract. Cystic, necrotic tumors or metastases may appear similar to abscesses.