Malignant transformation of liver adenoma: an analysis of the literature.

As adenoma in other locations, hepatic adenoma (HA) may transform into hepatocellular carcinoma (HCC) and hepatocyte dysplasia is most probably the intermediate step between both conditions. Malignant HA may appear as microscopic or macroscopic areas of HCC within the HA. These areas are typically well differentiated and without vascular extension or satellite nodules. AFP measurements are not reliable as they are usually normal. The risk of malignant transformation of HA cannot be reliably quantified yet. Several series are concordant to show that approximately 5% of patients whose HA have been resected had pathological evidence of HCC within their HA. This figure however does not take into account fully transformed HA where evidence of the preexisting benign lesion might have disappeared. The risk of malignant transformation is correlated with the diameter of the HA and it is very unusual when it is <5 cm and the same holds true for patients with multiple HA. These results suggest that small HA could be safely observed as they are also at low risk of bleeding. These conclusions might not apply to male patients who are at lower risk of HA, except in specific conditions, but appear to be at a much higher risk of malignant changes.