A 45-year-old woman with left lower quad- rant abdominal cramps is found to have a liver mass. Liver ultrasonography shows a 4-cm mass with uniformly increased echogenicity. The results of liver tests are normal. Contrast CT shows a 4-cm mass with peripheral nodular enhancement in the arterial phase and gradual fill-in of contrast in the later phases. 

A 28-year-old woman with abdominal pain has a 4-cm solid liver mass and two 2-cm simple liver cysts. She has been taking oral contracep- tives for 5 years but has no history of liver disease. On contrast CT, the mass enhances in the arterial phase and is isoattenuating in the venous phase. The imaging data are thought to be consistent with either focal nodular hyper- plasia or adenoma. Biopsy confirms focal nodular hyperplasia. The pain has since resolved. The most appropriate management of focal nodular hyperplasia in this patient is: 

A 35-year-old woman with dyspepsia has a 4-cm liver mass. She has no history of liver disease. She has taken oral contraceptives for 8 years. On CT with contrast, the mass enhances rapidly in the arterial phase and is isoattenuating in the venous phase. It has areas of heterogeneity, con- sistent with regions of hemorrhage and necrosis within the mass. The most appropriate man- agement of this mass is: 

A 72-year-old woman has sudden onset of painless jaundice and increased levels of bilirubin and alkaline phosphatase. CT of the abdomen shows a large 15- × 11-cm lobulated cyst in the right lobe of the liver, with mass effect on surrounding structures. Biliary scintigraphy shows no connection of the cyst to the biliary tree. Aspiration yields 950 mL of cloudy yellow fluid; cytology shows reactive cells, and cultures are negative. The most appropriate management of this cyst is: 

A 67-year-old man with chronic hepatitis C with cirrhosis, a platelet count of 80,000/mm3 (80×109/L), and serum total bilirubin of 1.2 mg/dL was referred for evaluation. The α-feto- protein level was 15.2 ng/mL. Recent abdom- inal CT findings were negative. EGD showed moderate-sized varices in the distal esophagus. Six months later, the α-fetoprotein level has increased to 250 ng/mL and ultrasonography shows a new 4.4-cm mass in the liver. Contrast CT shows arterial phase enhancement of the mass, with washout in the portal and venous phases. No other evidence of extrahepatic dis- ease is found. The diagnosis is: