Jiann-Sheng Su, Division of Gastroenterology and Hepatology, Kuang Tien General Hospital, Taichung 433, Taiwan.
Hepatoid adenocarcinoma (HAC) is a rare but important special type of extrahepatic adenocarcinoma with clinicopathological presentation mimicking hepatocellular carcinoma (HCC), and prompt and correct diagnosis can be a challenge, especially in endemic areas with a high incidence of HCC. To date, HAC has only been reported in case series or single case reports, so we aimed to review the clinicopathological characteristics of HAC to obtain a more complete picture of this rare form of extrahepatic adenocarcinoma. All the articles about HAC published from 2001 to 2011 were reviewed, and clinicopathological findings were extracted for analysis. A late middle-aged male with high serum α-fetoprotein and atypical image finding of HCC should raise the suspicion of HAC, and characteristic pathological immunohistochemical stains can help with the differential diagnosis. Novel immunohistochemical markers may be useful to clearly differentiate HAC from HCC. Once metastatic HAC is diagnosed, the primary tumor origin should be identified for adequate treatment. The majority of HAC originates from the stomach, so panendoscopy should be arranged first.