Spontaneous hepatocellular adenoma with marked cystic degeneration.

We report a case of spontaneous hepatocellular adenoma with marked cystic degeneration in the non-cirrhotic liver. A 36 year-old Japanese woman with neither history of liver diseases nor use of oral contraceptives and steroids, complained of a 6 kg weight loss over 6 months. Barium meal study revealed an extramural compression along the fornix of the stomach. Abdominal ultrasonography (UC) and computed tomography (CT) demonstrated a mass in the left lateral segment of the liver that measured 11.6x9.5 cm with cystic lesions. Laboratory data on admission showed no significant findings. Celiac angiography revealed a hyper-vascular mass. Surgical exploration revealed a soft mass arising and protruding from the left lateral segment of the liver. Partial resection of the left lateral segment was performed. Histologically, the tumor was surrounded by a thin fibrous pseudocapsule. The neoplastic cells resembling normal hepatocytes around the tumor were large, pale and arranged in thick, irregular cords. Neither mitotic figures nor foci of dysplasia were present. The central portions of the tumor showed marked cystic degeneration. The tumor was histologically diagnosed as hepatocellular adenoma (HCA). HCA with cystic degeneration has been rarely reported.