Selective necrosis of encapsulated malignant lesion within atypical adenomatous hyperplasia of the liver following transarterial embolization. A report of two autopsy cases.

We report here the morphology of two nodules of atypical adenomatous hyperplasia (AH), a preneoplastic or early developmental stage of hepatocellular carcinoma (HCC), with a fibrously encapsulated malignant lesion occurring in two cirrhotic livers. The two patients had been treated for HCC by transarterial embolization. At autopsy, HCC nodules and several AH nodules were found in each case. Microscopically, two of the several AH nodules contained malignant lesions that showed selective coagulative necrosis: the hepatocytes of the nonmalignant parts of the two AH nodules were viable. The malignant lesions within the atypical AH nodules were surrounded with a fibrous capsule, and the majority of HCC nodules were necrotic; AH nodules themselves, except for malignant lesions, were viable. This suggests to us that there are differences in blood supply between the malignant lesions and surrounding tissue of atypical AH: malignant lesions within atypical AH may be supplied mainly by arterial blood, whereas nonmalignant areas of atypical AH may be dually supplied by both arterial and portal blood. Alternatively, it may be that the malignant lesions in atypical AH are more susceptible to hypoxia caused by transarterial embolization.