Hepatoblastoma is a rare type of liver cancer that mainly affects young children, typically before their third birthday. While this diagnosis can feel overwhelming for any family, medical advances over recent decades have dramatically improved outcomes. Understanding what hepatoblastoma is, how it develops, and what treatment options exist can help parents and caregivers navigate this challenging journey with greater confidence and hope.

How Common Is Hepatoblastoma?

Hepatoblastoma is extremely rare. According to medical statistics, only about 1 to 2 children out of every million children in the United States develop this type of liver cancer each year. This makes it an uncommon condition even among childhood cancers, though it is the most frequent primary liver cancer diagnosed in children. The disease represents approximately 1 percent of all pediatric tumors, which means most pediatricians may only encounter a handful of cases throughout their entire careers.

The majority of hepatoblastoma cases appear in very young children. About half of all diagnoses occur before a child reaches their first birthday. Ninety percent of cases are discovered before age three. The condition becomes increasingly rare as children grow older, with most cases diagnosed during a child’s first three years of life. This pattern suggests that hepatoblastoma may be related to the way liver cells develop during early childhood.

Interestingly, medical researchers have noticed a gradual increase in the annual incidence of hepatoblastoma over the past few decades. This rise may be connected to improved survival rates among extremely premature babies. Babies born weighing less than one kilogram appear to face a substantially higher risk of developing this cancer later in early childhood. The increased medical ability to save very premature infants might partially explain why more cases are being diagnosed now than in previous generations.

What Causes Hepatoblastoma?

The exact cause of hepatoblastoma remains largely unknown to medical experts. What researchers do understand is that the disease begins when normal liver cells undergo certain changes in the way they function. Specifically, these cells begin to grow and divide in abnormal ways, forming tumors instead of healthy liver tissue. However, pinpointing why this happens in any particular child is usually not possible.

Most hepatoblastoma cases appear sporadically, meaning they occur without any obvious family history or identifiable cause. However, scientists have identified genetic mutations that appear to play a role in the disease. The most common genetic abnormality involves something called the Wnt signaling pathway, which leads to an accumulation of a protein called beta-catenin. These mutations are found in a significant proportion of sporadic hepatoblastoma cases—as many as 67 percent according to some studies.

Research also suggests that hepatoblastoma may originate from a pluripotent stem cell, which is a special type of cell that has the ability to develop into many different cell types. During normal development, these stem cells would mature into healthy liver cells. When something goes wrong in this process, they may instead form cancerous tumors. This theory helps explain why the disease primarily affects very young children, during the period when the liver is still developing rapidly.

While most cases have no clear cause, certain environmental and medical factors have been studied as possible contributors. Evidence suggests associations with parental tobacco smoking before and during pregnancy, though this does not mean smoking directly causes hepatoblastoma. Other factors that researchers have investigated include oxygen therapy given to premature babies, certain medications like furosemide, radiation exposure, and prolonged use of total parenteral nutrition (feeding through a vein). However, none of these factors can be definitively identified as causing the disease in individual children.

Risk Factors for Hepatoblastoma

Certain children face a higher risk of developing hepatoblastoma than others. One of the most significant risk factors is being born prematurely with very low birth weight. Babies born weighing less than 5 pounds, 5 ounces (or 2,408 grams) have an increased chance of developing this liver cancer. Similarly, infants born before 37 weeks of gestation are considered at higher risk.

Several genetic syndromes and inherited conditions substantially increase a child’s likelihood of developing hepatoblastoma. Beckwith-Wiedemann syndrome is one such condition that affects growth and raises cancer risk. Children with this syndrome may develop faster than typical and have larger organs than usual. Familial adenomatous polyposis, abbreviated as FAP, is another important risk factor. This condition causes numerous precancerous growths called polyps to develop in the colon, and children with FAP have a notably higher chance of developing hepatoblastoma.

Other genetic conditions associated with increased hepatoblastoma risk include Aicardi syndrome, which causes brain malformations and affects other body systems. Edwards syndrome, also known as trisomy 18, affects how a child’s body develops and grows overall. Hemihyperplasia causes one side of a child’s body to grow faster than the other side. Simpson-Golabi-Behmel syndrome leads to abnormalities in the liver and other organs from birth.

Additional medical conditions linked to hepatoblastoma include biliary atresia, which blocks the bile ducts in babies and damages the liver, and glycogen storage disease, which affects how the body processes sugar. Some children with Down syndrome (trisomy 21) may also have increased risk. It is important to note that even when these risk factors are present, most affected children will never develop hepatoblastoma. The increased risk means these children benefit from closer monitoring, not that cancer is inevitable.

Recognizing the Symptoms

Hepatoblastoma grows very slowly, which means children often do not show any symptoms until the tumor becomes quite large. This delayed appearance of symptoms can make early detection challenging. Parents may not notice anything wrong with their child for weeks or months while the tumor gradually increases in size within the liver.

The most common symptom that eventually brings families to seek medical care is swelling or enlargement of the child’s belly, technically called the abdomen. Parents might notice that their child’s stomach looks bigger than usual or seems to stick out more than normal. Sometimes a firm lump can be felt in the middle or upper right side of the abdomen during a physical examination. This mass may be large enough that parents can feel it themselves, or it may only be detectable by a doctor.

Other symptoms that children with hepatoblastoma may experience include pain or discomfort in the belly area. This pain might be persistent rather than coming and going. Many children lose their appetite and stop eating as much as they normally would, which leads to unexplained weight loss. Parents might notice their child seems less interested in food or refuses meals they previously enjoyed.

Some children experience persistent nausea and vomiting, which can make eating even more difficult. More visibly alarming, the child’s skin and the whites of their eyes may develop a yellow color. This symptom is called jaundice and occurs when the liver cannot properly filter certain substances from the blood. Other possible symptoms include fever without an obvious cause, itchy skin, fatigue or tiredness, back pain, and decreased urination.

It is crucial to understand that many common childhood illnesses can cause similar symptoms, particularly stomach pain, vomiting, and loss of appetite. Hepatoblastoma is extremely rare, so chances are good that these symptoms have a much more common cause. However, if symptoms persist, especially if accompanied by a growing belly or visible lump, parents should trust their instincts and contact their child’s pediatrician. Only a healthcare provider can determine whether these symptoms require further investigation.

How to Prevent Hepatoblastoma

Unfortunately, there is no known way to prevent hepatoblastoma in most cases. Because the exact causes remain unclear and most cases appear without warning in children with no identifiable risk factors, specific prevention strategies do not exist. Parents should understand that there is nothing they could have done differently to prevent their child from developing this cancer.

For children with known genetic conditions that increase hepatoblastoma risk, prevention takes the form of early detection through regular screening. Children diagnosed with Beckwith-Wiedemann syndrome, hemihyperplasia, Simpson-Golabi-Behmel syndrome, or trisomy 18 should receive abdominal ultrasound examinations every three months from birth or from the time their risk condition is diagnosed. These screening tests continue until the child reaches age four, after which the risk drops significantly.

Along with imaging tests, children at increased risk have their blood tested regularly to measure levels of a protein called alpha-fetoprotein, abbreviated as AFP. This protein is normally high in newborns but drops to low levels by age two. Unusually elevated AFP levels can signal the presence of liver cancer before any symptoms appear. Regular monitoring allows doctors to catch tumors at earlier, more treatable stages.

For the general population without specific risk factors, maintaining overall good health during pregnancy may help reduce risks, though this has not been definitively proven. Avoiding tobacco smoke before and during pregnancy is advisable, as some research has shown associations between parental smoking and hepatoblastoma. Pregnant women should follow their obstetrician’s recommendations for prenatal care. For premature babies who require intensive medical care, parents should understand that the treatments keeping their baby alive are essential, even though some factors associated with prematurity care have been studied in relation to hepatoblastoma risk.

How the Body Changes with Hepatoblastoma

To understand how hepatoblastoma affects a child’s body, it helps to know what the liver normally does. The liver is one of the largest organs in the body, positioned in the upper right side of the abdomen beneath the rib cage. This vital organ has multiple lobes and performs many essential functions. It produces bile, which helps digest fats from food. It stores glycogen, a form of sugar that the body uses for energy. It also filters harmful substances from the blood so they can be eliminated from the body through stool and urine.

Hepatoblastoma tumors form when immature liver cells, called precursor cells, begin growing abnormally instead of developing into normal, functioning liver tissue. The cancer cells resemble fetal liver cells—the kind that exist before birth—rather than mature adult liver cells. This is why the disease primarily affects very young children, during the time when liver tissue is still developing and maturing rapidly.

The tumors typically grow as single masses, though sometimes multiple tumors can develop. They more commonly affect the right lobe of the liver compared to the left lobe. As the tumor grows larger, it takes up space that should contain healthy liver tissue. This growing mass can press against other organs in the abdomen, causing pain and the visible swelling that parents often notice first.

When the tumor becomes large enough, it can interfere with the liver’s normal functions. If the tumor blocks bile ducts, bile cannot flow properly, leading to jaundice—the yellowing of skin and eyes that occurs when bile components build up in the bloodstream. The liver’s reduced ability to filter the blood and produce necessary proteins can cause various problems throughout the body.

In some cases, hepatoblastoma can spread beyond the liver to other parts of the body through a process called metastasis. The most common sites for metastasis are the lungs and the lymph nodes located around the abdomen. When cancer cells break away from the original tumor and travel through the bloodstream or lymphatic system, they can establish new tumors in these distant locations. Less commonly, hepatoblastoma may spread to bone or brain tissue. The tendency to metastasize makes early detection and complete surgical removal of tumors particularly important.

Different types of hepatoblastoma have been identified based on how the cancer cells look under a microscope, called the histology. The main categories are epithelial type and mixed type. Within these categories, doctors distinguish between well-differentiated fetal histology, mixed epithelial and fetal histology, and small cell undifferentiated histology. These histological differences affect how aggressive the cancer behaves and influence treatment decisions. Generally, well-differentiated tumors respond better to treatment, while small cell undifferentiated types tend to be more aggressive and harder to treat.