Hepatic Mass in a Child

Alexander J. Towbin, MD

DIFFERENTIAL DIAGNOSIS

Common

Hepatoblastoma
Hepatocellular Carcinoma
Hemangioendothelioma

Less Common

Abscess
Focal Nodular Hyperplasia
Metastases

Rare but Important

Choledochal Cyst
Mesenchymal Hamartoma
Embryonal Sarcoma
Hepatic Adenoma
Angiomyolipoma (AML)
Nodular Regenerative Hyperplasia
Fibrolamellar Hepatocellular Carcinoma
Biliary Rhabdomyosarcoma
Angiosarcoma

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Primary hepatic neoplasms uncommon in children
- 0.5-2% of all pediatric neoplasms
- 2/3 malignant
Differential diagnosis can be focused by age
Biopsy often needed for diagnosis

Helpful Clues for Common Diagnoses

Hepatoblastoma
- Most common pediatric liver malignancy
  - 1% of all pediatric malignancies
  - 79% of all liver malignancies < 15 years of age
  - Majority diagnosed under 18 months
- More common in boys
- Associated with low birth weight, hemihypertrophy, Beckwith-Wiedemann, familial adenomatous polyposis, trisomy 18, and fetal alcohol syndrome
- Often presents as asymptomatic mass
- 90% have increased serum AFP
- Most common in right lobe of liver, bilateral in 35%
- Calcifications occur in 40-55%
- Distant metastases in 20% at diagnosis
  - Lung most common, followed by brain and bone
- Staged via PRETEXT staging system
- Treatment via resection
  - Contraindications: Extensive bilateral disease, vascular invasion, or distant metastases
- 75% 5-year survival rate
Hepatocellular Carcinoma
- 2nd most common liver malignancy in children
  - Rare before age 5
  - More common in males
- ˜ 75% not associated with liver disease
- Risk factors: Preexisting cirrhosis due to biliary atresia, Fanconi syndrome, viral hepatitis, or glycogen storage disease
  - Other risks: Androgen steroids, oral contraceptives, methotrexate
- Metastases common at diagnosis
  - Regional lymph nodes, lungs, bone
- Elevated AFP in 60-80%
- Staged via PRETEXT system
- Poor long-term survival
Hemangioendothelioma
- a.k.a. infantile hemangioendothelioma
- Most common benign hepatic tumor
- 85% diagnosed in 1st 6 months
- Often asymptomatic in childhood
- Skin hemangiomas present in ˜ 50%
- Hint: High-output heart failure + liver tumor

Helpful Clues for Less Common Diagnoses

Abscess
- Associated with bacteremia, parasites, and chronic granulomatous disease
- Can be seen with inflammatory process involving bowel
Focal Nodular Hyperplasia
- Occurs in all age groups
- Well-circumscribed lobulated lesion with central stellate scar
- More common in females and in patients who have received chemotherapy
Metastases
- Neuroblastoma and Wilms most common

Helpful Clues for Rare Diagnoses

Choledochal Cyst
- Cystic or fusiform dilation of biliary tree
- Todani classification with 5 types
  - Type 1 most common
- Associated with ductal and vascular anomalies
  - Anomalous hepatic arteries, accessory ducts, and primary duct strictures
- Ultrasound is best screening test
- Treated with excision due to risk of malignant degeneration
Mesenchymal Hamartoma
- 2nd most common benign hepatic tumor of childhood
  - 6-8% of pediatric hepatic neoplasms
  - 85% present before age 3
- Often present as large RUQ mass
  - 75% in right lobe
  - AFP can be elevated
- Multiloculated cystic mass
  - Tiny cysts can give solid appearance
  - On US, septae of cysts may be mobile
  - Large portal vein branch may feed mass
  - Calcification uncommon
- Associated with congenital heart disease, malrotation, esophageal atresia, annular pancreas, biliary atresia, and exomphalos
  - Also associated with myelomeningocele and Beckwith-Wiedemann syndrome
- Rare malignant degeneration to undifferentiated embryonal sarcoma
- Treatment via excision
Embryonal Sarcoma
- a.k.a. undifferentiated sarcoma
- Accounts for 9-15% of all hepatic tumors
  - 3rd most common malignant hepatic tumor in children
- Usually occurs between 6-10 years of age
- On US, appears as solid mass with cystic areas
- On CT, appears hypodense with septations and fibrous pseudocapsule
- Case reports of spontaneous rupture
- 4-year survival: 70-83%
Hepatic Adenoma
- Most common in young women
- ↑ risk with oral contraceptive or anabolic steroid use
Angiomyolipoma (AML)
- Associated with tuberous sclerosis
- Less common than renal AML
Nodular Regenerative Hyperplasia
- Multi-acinar regenerative lesion of liver
- Associated with systemic diseases
- 1/2 of patients have portal hypertension
Fibrolamellar Hepatocellular Carcinoma
- Occurs in adolescents, young adults
- Calcifications seen in 35-68%
- Central scar present in 20-71%
  - Low signal on all MR pulse sequences
- Dismal prognosis if not resectable
Biliary Rhabdomyosarcoma
- Accounts for 0.5% of rhabdomyosarcomas
- Intraductal mass on CT or MR
Angiosarcoma
- a.k.a. hemangioendothelioma, type 2
  - M:F = 1:2
  - Mean age: 3-4 years
- Resembles hemangioendothelioma
- Tumor usually involves both lobes
- Metastases to lungs, nodes, pleura, bones, and adrenals