Infantile mesenchymal hamartoma of the liver with elevated alpha fetoprotein.

Mesenchymal hamartoma of the liver (MHL) is a benign tumour that most commonly occurs in children. In most cases of MHL, the α fetoprotein (AFP) level is within the normal limits, only in a few cases, increased AFP has been described which usually causes misdiagnosis of hepatoblastoma. We report a case of a 3-month-old paediatric patient who was incidentally detected with a very high level of AFP, at 6388.4 ng ml-1. Ultrasound revealed a right liver tumour, segment VI, measuring at 56 × 53 mm. According to images of ultrasound and MRI, the diagnosis was mesenchymal hepatic sarcoma. The paediatric patient had surgery to remove the entire liver segment containing the tumour. Micropathological examination showed that the tumour was a MHL. The serum AFP level fell rapidly to near normal following the surgery. The MHL benign liver tumour with an atypical presentation caused a very high AFP level. This was a rare clinical case, and it was difficult to diagnose.

Pre-S2 deletion mutants of hepatitis B virus could have an important role in hepatocarcinogenesis in Asian children.

Although many studies on the risk factors and their carcinogenesis in adult hepatocellular carcinoma (HCC) have been reported, they remain poorly understood in childhood HCC. A retrospective study of 42 HCC cases in Asian children was conducted. Hepatitis B virus (HBV)-DNA in HCC tissues was detected in 36 of 42 (86%) cases tested, while no hepatitis C virus (HCV)-RNA was detectable in any of HCCs. Twenty of 36 (56%) HCC cases were accompanied by cirrhosis. Surprisingly, very high prevalence of the HBV pre-S deletion mutant was recognized in 27 of 30 (90%) HCCs examined. They occurred most frequently in pre-S2 (20/27, 74%) followed by pre-S1 (5/27, 18.5%), and both pre-S1/S2 (2/27, 7.4%). Interestingly, the pre-S2 mutant consistently appeared with deletion at nt 4-57 in all of the 20 cases with the pre-S2 mutant (100%) and within this locus in the two cases with both pre-S-1/S2 mutants. Type II ground-glass hepatocytes in non-tumorous livers were seen in 15 of the 22 HCCs with the pre-S2 deletion mutant (68%). This hotspot mutation in the pre-S2 was further confirmed by complete genomic sequence of HBV in a Japanese boy who eventually developed HCC. Our result strongly suggests that HBV is a major contributor to the development of HCC in Asian children. The HBV pre-S2 deletion mutant at nt 4-57 which has a CD8 T-cell epitope could be responsible for the emergence and aggressive outcome of childhood HCC. Determination of this hotspot mutation in the pre-S2 region could be a useful index for predicting the clinical outcome of HCC development.