Chapter 458

Liver tumors represent approximately 1% of all childhood cancers. There are approximately 100 to 150 new cases of liver cancer diagnosed in children each year in the United States.1 Hepatoblastoma is the most common malignant tumor of the liver and accounts for two thirds of all liver cancer in children.2 Hepatoblastoma occurs almost always in the very young child, with a mean age of onset of approximately 18 to 20 months and 95% of cases occurring before 5 years of age. The incidence of hepatoblastoma has approximately doubled over the past few decades.3 Hepatoblastoma is considered an embryonal tumor because histologically, tumor cells resemble cells seen in the developing liver.

Hepatocellular carcinoma is the primary liver malignancy in older children and adolescents. The male-to-female ratio is approximately 1.5:1 for hepatoblastoma and hepatocellular carcinoma. Other less common liver tumors include undifferentiated embryonal sarcoma, rhabdoid tumor, angiosarcoma, rhabdomyosarcoma of the biliary tract, cholangiocarcinoma, and other germ cell tumors. One third of all tumors of the liver in children turn out to be benign entities that include vascular tumors (hemangioendotheliomas), mesenchymal hamartomas, and adenomas.4

As with most types of pediatric cancers, the underlying causes are largely unknown; however, several genetic syndromes are associated with hepatoblastoma, and epidemiologic studies have provided some clues to their etiology.

Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome characterized by large birth weight, macroglossia, omphalocoele, and visceromegaly. Children with BWS are at risk of developing embryonal tumors including Wilms tumors, hepatoblastoma, neuroblastoma, and adrenocorticocarcinoma. A national registry of children with BWS reports that the risk of children with BWS developing hepatoblastoma is 2280-fold higher than the general population and that the risk for hepatoblastoma was significantly higher than for Wilms or any other type of cancer in children with BWS. Screening children with BWS with periodic abdominal ultrasounds and serum alpha-fetoprotein levels every 3 months during the first decade of life may be associated with detection at an early stage and is therefore recommended.5

Familial adenomatous polyposis (FAP), an autosomal dominant syndrome characterized primarily by polyp growth in the colon which begins in adolescence and without intervention progresses to colon cancer, is also associated with a high risk of hepatoblastoma.6 Mutation in the causative adenomatous polyposis coli (APC) gene can be readily detected in children with hepatoblastoma who have a family history of early onset colon cancer. These children are clearly at risk for polyps and colon cancer and need follow-up with lifelong surveillance. It is less clear how great the risk of carrying such a cancer predisposition is in other children with hepatoblastoma without a clear history of FAP, but it has been suggested that children with hepatoblastoma be screened for APC mutations and also that asymptomatic children from FAP families be screened for mutation carrier status and for hepatoblastoma if APC mutations are detected.

In addition to BWS and FAP, several other syndromes ...

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