Liver Tumors in Pediatrics

Overview

Primary liver tumors are rare in children, but 60% are malignant.
Two most common liver tumors:
- Hepatoblastoma (80% of malignant liver tumors).
- Hepatocellular carcinoma (HCC).

Hepatoblastoma:
- Accounts for 1% of pediatric cancer.
- Peak incidence: 3 years of age.
- More than 90% of liver tumors in patients younger than 5 years.
HCC:
- Common in children aged 10-11 years.
- 87% of liver tumors in patients aged 15-19 years.
Risk factors:
- Hepatoblastoma: Familial adenomatous polyposis, Gardner syndrome, Beckwith-Wiedemann syndrome.
- HCC: Acquired hepatitis B and C, congenital diseases (e.g., tyrosinemia, glycogen storage disease, α1-antitrypsin deficiency).

Symptoms:
- Painless palpable abdominal mass.
- Non-specific symptoms: Anorexia, weight loss, abdominal pain, failure to thrive.
- Jaundice: Uncommon except in advanced cases.
- Some patients may present with tumor rupture, causing intraabdominal bleeding and peritonitis.
AFP levels: Elevated in >70% of patients.

Symptoms:
- Similar presentation to hepatoblastoma.
- Stigmata of cirrhosis: Jaundice, spider angiomas, ascites, splenomegaly.
- Metastatic spread: To abdominal/mediastinal lymph nodes, lungs, bone marrow, brain (in 25% of patients).
- Blood abnormalities: Anemia, thrombocytopenia, or pancytopenia (due to splenomegaly).
Testing: All children should be tested for hepatitis B and C exposure.

Initial study: Abdominal ultrasonography.
- Doppler ultrasound: Detects tumor extension into or thrombosis of major vessels (e.g., hepatic veins, IVC, portal vein).
CT scan: Essential for assessing the tumor's relationship to vital structures and intraabdominal tumor extension.
Chest CT: Recommended to check for lung metastases.
Bone scintigraphy: Recommended for staging HCC due to a high incidence of bone metastases.

Hepatoblastoma:
- Typically a unifocal mass with a pseudocapsule.
- May have epithelial (fetal/embryonal) or mixed epithelial and mesenchymal components.
Hepatocellular Carcinoma (HCC):
- Characterized by large, pleomorphic epithelial cells resembling mature hepatocytes.
- Often multifocal, with diffuse intrahepatic involvement.

TNM staging: Used for hepatoblastoma.
PRETEXT system:
- Developed by the International Childhood Liver Tumor Strategy Group (SIOPEL).
- Classifies tumors based on the number of tumor-free sections of the liver.
- High-risk factors include:
  - AFP levels > 100 ng/mL.
  - Metastases.
  - Intraperitoneal hemorrhage.
  - Vascular invasion (hepatic veins, IVC, portal vein).
  - This system takes caudate lobe involvement, tumor rupture, ascites, extension into the stomach or diaphragm, tumor focality, lymph node involvement, presence of distant me- tastases, and vascular involvement into further consideration [ sabiston]

Hepatoblastoma: Tumors in PRETEXT I and II can be resected via segmentectomy or anatomic lobectomy.
HCC: Partial hepatectomy is attempted, but recurrence rates are high.

Liver transplantation is an option for unresectable tumors.
Criteria for transplantation:
- No more than 3 tumors, each <3 cm.
- No extrahepatic disease or vascular invasion.

Neoadjuvant chemotherapy: Used to shrink tumors before resection.
- Can also treat microscopic residual disease to reduce recurrence.
Chemotherapy regimens:
- Hepatoblastoma: Cisplatin, 5-fluorouracil, vincristine.
- Relapse: Doxorubicin, irinotecan, ifosfamide.
- Direct arterial chemotherapy/chemoembolization: Used for chemo-resistant tumors.

Hepatoblastoma:
- 85%-90% long-term survival for resectable tumors.
- Similar survival rates with liver transplantation for unresectable tumors.
HCC:
- Survival rates with partial hepatectomy remain poor.
- Early transplantation has shown improved outcomes in some centers.

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