Hepatic Malignancies

Primary hepatic tumors are relatively uncommon in the pediatric population. They are mainly represented by hepatoblastoma and hepatoma, while other malignant tumors such as angiosarcoma, undifferentiated embryonal sarcoma and embryonal rhabdomyosarcoma of the biliary tree are limited to a very few cases.

Hepatoblastoma
Hepatoblastoma is the most common liver tumor in children. It accounts for nearly 27% of all pediatric hepatic tumors and 47% of those that are malignant. Hepatoblastoma is seen in children primarily under the age of 2 years. Eighty-eight  per cent of hepatoblastoma are found  in children less than 5 years old, only 3% in patients older that 15 years, which suggests the presence of a genetic component. The most frequent abnormality appears to be the trisomy of chromosome 20, followed by trisomy of chromosome 2. Molecular genetic studies have shown abnormalities on the short arm of chromosome 11. Associated conditions are present in 5% of cases.  Laboratory tests in children with hepatoblastoma are usually unremarkable except for the frequent elevation of serum-fetoprotein &. Histologically, the tumor has been classified into six patterns.
Complete surgical resection is the definive treatment for hepatoblastoma. However, at time of diagnosis, as many as 70% of cases may be unresectable. The most important advancement in the management of children with hepatoblastoma has been the discovery that effective chemotherapeutic agents can convert extensive, unresectable tumors into tumors that can be completely removed by surgery, dramatically increasing the likelihood of cure &. 
Liver transplantation is  accepted as a treatment for patients with unresectable hepatoblastoma $ after chemotheraphy,  with reported patient survival rates at 1 and 5 years between 80% and 88% and 65% and 80%, respectively.

Hepatocellular carcinoma
Hepatocellular carcinoma is the third most frequently diagnosed pediatric tumor, it is highly malignant and occurs primarily in the older pediatric patients, with over 65% of cases seen in children over 10 years of age.  A wide variety of associated conditions are seen in 20% to 25% of cases. One of the closest associations is with hereditary tyrosinemia, with 37% of the patients surviving beyond 2 years of age developing hepatocellular carcinoma &.  As for adults, an association between hepatocellular carcinoma and hepatitis virus B infection has been documented &.
Hepatocellular carcinoma $ may be single or multicentric masses with involvement of both right and left liver in over 70% of cases.  The surrounding liver may show a micro- or macronodular cirrhosis in about 15% of cases. Microscopically $, 2 different patterns, with different prognoses, can be recognized: the “usual” type and the fibrolamellar variant &.
In children with an otherwise normal liver the treatment of hepatocellular caricnoma is directed toward surgical resection of the lesion, followed by chemotherapy and/or radiation therapy. Resectability at time of diagnosis was reported between 3% to 40% &. Long term survival  was achieved in 15% to 20% of cases &.  Patients with the fibrolamellar  variant have a somewhat better prognosis &.
Somewhat disappointing results obtained with conventional surgery suggested the use of liver transplantation. Results were good in patients with incidental hepatocarcinoma discovered at pathological or operative examination and in children who underwent transplantation for other primary liver diseases who had known associated hepatocarcinoma, but were discouraging in children with primary hepatocarcinoma without another primary liver disease.

Other primitive tumors
Other primitive malignant tumors are represented by undifferentiated embryonal sarcoma, hemangioendothelioma $, hemangiosarcoma $ and  embryonal rhabdomyosarcoma $ of the biliary tree, endodermal sinus (yolk salk) tumor, leiomyosarcoma, malignant rhabdoid tumors and lymphoma and account for less than 3% of all primitive malignant neoplasm. Treatment, including resection, radiation therapy and a variety of chemiotherapeutic agents has been  unsuccessful and patients rarely survived for more than 3 years.
Liver transplantation has been successfully performed only for hemangioendothelioma and in few patients with angiosarcoma with recurrence of the disease.
Transplantation for benign liver tumors is performed only for extensive liver involvement that cause hepatic failure or life-threatening complications, when medical therapy or conventional surgical resection are not effective.