Hepatoblastoma is a rare cancerous tumor that develops in the liver, almost exclusively in young children. It is the most common liver cancer in children, with the highest rates occurring in infants under one month old, at roughly 2.57 per 100,000 newborns. Most cases are diagnosed before age 3, and the tumor typically shows up as a rapidly growing mass in the abdomen.
How Hepatoblastoma Develops
Despite its name, hepatoblastoma doesn’t always originate from hepatoblasts (the immature liver cells present during fetal development). The tumor can arise from several different cell types along the liver’s developmental spectrum. The “fetal” subtype, which has cells that closely resemble near-mature liver cells, tends to behave less aggressively. The “embryonal” subtype originates from earlier, less developed cells and often behaves more aggressively. A rare “small cell undifferentiated” form comes from the earliest liver stem cells and carries a worse prognosis.
The key genetic driver in many hepatoblastoma cases is a mutation that activates a signaling pathway involved in cell growth and development. This pathway, called Wnt/beta-catenin, normally helps regulate how cells multiply and organize themselves. When it’s switched on permanently through a mutation, liver cells can grow unchecked.
Who Is at Risk
Most children who develop hepatoblastoma have no identifiable risk factor. However, up to 15 percent of patients have an underlying genetic condition that predisposes them to the tumor. The three syndromes most strongly linked to hepatoblastoma are Beckwith-Wiedemann syndrome, Simpson-Golabi-Behmel syndrome, and familial adenomatous polyposis (FAP).
Beckwith-Wiedemann syndrome stands out for its striking degree of risk. Children with this overgrowth disorder have a relative risk 2,280 times higher than the general pediatric population during the first four years of life. The risk varies depending on which specific genetic change a child carries, so molecular testing helps guide how closely these children are monitored. Some children with hepatoblastoma are also born larger than average for gestational age, which likely reflects the overlap between hepatoblastoma risk and overgrowth syndromes.
Very low birth weight and prematurity have also been identified as independent risk factors, which is notable because it sits at the opposite end of the growth spectrum from overgrowth syndromes. The biological explanation for this link is still not fully understood.
Signs and Symptoms
The most common first sign is a firm, painless mass in the upper right side of a child’s abdomen. Parents or a pediatrician often notice it during a bath or routine checkup when the belly looks swollen or feels unusually hard. The mass can grow quickly over days to weeks.
Other symptoms include abdominal discomfort or pain, loss of appetite, vomiting, fatigue, and sometimes unexplained weight loss. Because these symptoms overlap with many common childhood illnesses, a visible or palpable abdominal mass is usually what triggers further investigation.
How It Is Diagnosed
A blood test measuring alpha-fetoprotein (AFP) plays a central role in diagnosis, but interpreting it in very young children is tricky. Newborns normally have extremely high AFP levels, typically between 17,200 and 44,300 ng/mL. These levels drop steadily over the first eight months of life, eventually settling to adult values of around 10 to 15 ng/mL. Because of this natural decline, a tumor-produced spike in AFP may not stand out against the already-high background levels in a baby under four months old. Only about half of hepatoblastoma cases show AFP levels above the expected range for the child’s age during this early window.
AFP becomes far more useful after the first year of life, when any significant elevation strongly suggests a liver tumor or germ cell tumor. It is also invaluable for tracking treatment response. After surgery, AFP levels should fall back to normal. If they don’t, it signals that tumor cells remain. A later rise in AFP, even without any visible tumor on imaging, is an early warning sign of recurrence.
Imaging with ultrasound is typically the first step, followed by CT or MRI to map the tumor’s exact location and size within the liver. A biopsy confirms the diagnosis and identifies the tumor’s subtype.
The PRETEXT Staging System
Hepatoblastoma uses a unique staging system called PRETEXT, which stands for PRE-Treatment EXTent of tumor. It divides the liver into four sections and classifies tumors based on how many sections are involved before any treatment begins.
- PRETEXT I: Tumor in one section, with the three neighboring sections free of disease.
- PRETEXT II: One or two sections involved, with two neighboring sections free.
- PRETEXT III: Two or three sections involved, with only one neighboring section free.
- PRETEXT IV: All four sections contain tumor.
Additional letters are added to note whether the tumor has spread into major blood vessels (V for hepatic veins, P for the portal vein) or beyond the liver (F for distant spread, such as to the lungs). These details directly determine whether surgery can safely remove the tumor or whether a liver transplant will be necessary.
Treatment: Chemotherapy and Surgery
Treatment for hepatoblastoma almost always combines chemotherapy with surgery, and the sequence depends on whether the tumor can be removed at diagnosis. If a surgeon can safely remove the tumor right away, surgery comes first, followed by chemotherapy to eliminate any remaining microscopic disease. If the tumor is too large or involves too many blood vessels for safe removal, chemotherapy is given first to shrink it.
The standard chemotherapy approach in North America uses a combination of cisplatin with other agents, given in four cycles before surgery. After the tumor is completely removed, two additional cycles are typically administered. European protocols follow a similar philosophy, using a combination of cisplatin and doxorubicin before surgery.
For children with early-stage disease (stage I or II) and certain favorable tumor subtypes, treatment can sometimes be less intensive. In a large North American trial, nearly all patients with stage I or II disease received just two cycles of chemotherapy after surgery, reflecting efforts to reduce treatment side effects when the tumor biology is favorable.
When a Liver Transplant Is Needed
Most children with hepatoblastoma are treated with tumor resection, meaning a surgeon removes the portion of the liver containing the cancer. The liver regenerates remarkably well, especially in young children, and the remaining tissue grows back to near-normal size within weeks.
A liver transplant becomes the better option when the tumor involves all four sections of the liver (PRETEXT IV), invades major blood vessels like the portal vein or hepatic veins, or fails to shrink enough with chemotherapy to allow safe partial removal. Current guidelines from both American and European pediatric liver tumor groups define specific criteria for transplant evaluation based on these factors.
Local recurrence (the tumor returning at the original site) is more common after standard resection, occurring in about 14 percent of cases compared to 3 percent after transplant. However, distant recurrence, where the cancer appears in other organs like the lungs, is more frequent after transplant (16 percent versus 5 percent after resection). For selected patients with locally advanced tumors, resection can be an effective alternative to transplant when the surgeon determines enough healthy liver can be preserved.
Outlook and Survival
Hepatoblastoma is one of the more treatable childhood cancers when caught before it spreads. Children with tumors that are completely removed by surgery and respond well to chemotherapy have survival rates above 80 percent at five years, with some studies reporting rates over 90 percent for early-stage, favorable-subtype disease. The prognosis drops significantly when the cancer has spread to the lungs or other organs at diagnosis, or when the tumor is the small cell undifferentiated subtype.
AFP levels after treatment remain one of the most reliable tools for long-term monitoring. Even years later, a rising AFP level is often the earliest indicator that the tumor has returned, sometimes appearing before anything shows up on imaging. Children who complete treatment are followed closely with regular blood tests and imaging for several years, with the most intensive surveillance during the first two years after finishing therapy.