Liver volumes at the initial and last CT examinations and an increase in or late occurrence of ascites are useful prognostic findings.

Angiomyolipoma is a benign mesenchymal tumor that has been reported frequently in the kidney but rarely in the liver. In the present study, we present four cases of hepatic angiomyolipoma with different radiologic appearances, discuss differential diagnosis, and review previously reported cases. One of our cases was followed for 8 years. Computed tomography (plain, enhanced, and dynamic study), magnetic resonance imaging (T1-weighted spin echo, T2-weighted spin echo, and dynamic study), ultrasonography, and angiography were performed in all cases. Although different radiologic appearances were observed in the tumors, based on different proportions of fat, blood vessels, and muscle, three cases were diagnosed as angiomyolipoma. In one case, it was quite difficult to make radiologic diagnosis; hepatocellular carcinoma with fatty metamorphosis in part was most likely suspected, but histopathological examination revealed angiomyolipoma with few fat elements. In the present study, early and prolonged enhancement of the lesion with the special pattern of time density/intensity curve was significant for angiomyolipoma, and we suggest that preoperative radiologic diagnosis of the lesion is possible in most of the cases. However, it can be quite difficult to distinguish angiomyolipoma from some hepatocellular carcinomas with fatty metamorphosis.

Early appearance of radiation-induced hepatic injury was found only to be gender dependent, with a tendency to occur with higher irradiated doses; no other parameters affected this phenomenon in our cases. Disappearance of the injured areas, if present, takes a long time (at least 42 months).

Despite our limited experience, VMC lesions seem to show some CT and MR features different from those of other multiple small hepatic lesions. They presented as multiple or numerous intrahepatic tiny cystoid lesions usually with irregular contour, scattered throughout the liver up to the subcapsular areas, and were detected in far greater number by enhanced CT or T2-weighted MR images than by unenhanced CT or T1-weighted images. They showed no remarkable change on long term follow-up imaging. We propose that a diagnosis of typical VMC could be made after analyzing CT or MR images carefully with good understanding of its pathologic basis, but imaging follow-up is necessary in oncology patients.

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