Hepatoblastoma is the most common primary liver malignancy in infants and young children. It is usually diagnosed before the third year of life and is twice as common in boys than in girls. Most cases are sporadic, but the condition can also be associated with congenital abnormalities such as Beckwith-Wiedemann syndrome, trisomy 18, trisomy 21, Aicardi syndrome, Li-Fraumeni syndrome, and familial adenomatous polyposis. Extremely premature infants with birth weight <1 kg have greatly increased risk of hepatoblastoma development. There have been isolated cases of hepatoblastomas in older children and adults; these tend to have a poorer prognosis.

Hepatoblastomas present as a rapidly growing singular well-circumscribed solid mass. They are more common in the right hepatic lobe. Due to rapid growth, rupture and hemorrhage are potentially deadly complications if unrecognized. Microscopically, these tumors are composed of embryonal and fetal hepatic elements. Prognosis is based on histologic type, with well-differentiated pure tumors having the best prognosis and poorly differentiated small cell tumors having the worst prognosis.

Symptoms include abdominal swelling, abdominal pain, vomiting, poor feeding or feeding intolerance, weight loss, anorexia, and irritability. Serum alpha fetoprotein (AFP) is elevated in 80%-90% of patients. Tumor rupture may present with vomiting, peritonitis, and severe anemia.