Case report: right-sided periadrenal metastasis supplied by the hepatic artery. Clue to the genesis of pedunculated hepatocellular carcinoma.

The adrenal is the second most common site of haematogenous metastasis of hepatocellular carcinoma (HCC). The right adrenal is much more frequently affected than the left, but no reason has been offered for this difference. An aetiological connection has never been suggested between adrenal metastasis and pedunculated HCC. Hepatocellular carcinoma was resected in two patients who subsequently developed right-sided adrenal metastasis diagnosed by imaging. The adrenal mass was enhanced by hepatic arteriography and took up lipiodol injected into the hepatic artery. Reoperation was performed to remove the adrenal mass, which was abutting on the liver but was readily separable. Histopathologically, the adrenal gland was compressed by a metastatic HCC that developed in the immediate periadrenal tissue or adrenal capsule. By conventional imaging, the adrenal gland could not be recognized and the mass was thought to have arisen within the adrenal gland. In conclusion, periadrenal growth of HCC is a hitherto unrecognized type of metastasis and must have been mistaken either for an adrenal metastasis or a pedunculated HCC in the past. If left unresected, it would have fused with the liver and grown into a pedunculated HCC. Cancer cell invasion through an adrenohepatic fusion is the most likely mode of periadrenal metastasis; it explains the arterial communication between the mass and the liver.