Hepatic Mass in a Neonate

Alexander J. Towbin, MD

DIFFERENTIAL DIAGNOSIS

Common

Hemangioendothelioma/Hemangioma
Metastases
- Neuroblastoma
- Wilms Tumor
Hepatoblastoma
Mesenchymal Hamartoma

Less Common

Unilocular Cyst
Choledochal Cyst

Rare but Important

Abscess
Angiosarcoma

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Hepatic tumors uncommon in perinatal period
- Account for ˜ 5% of perinatal tumors
- 6x more likely to be benign
- Most masses identified during antenatal US or neonatal physical exam
Lab tests can help to differentiate masses
- CBC, α-fetoprotein (AFP), β-HCG, are markers for neuroblastoma
Biopsy or resection provide final diagnosis
- Overlap of imaging and clinical finding

Helpful Clues for Common Diagnoses

Hemangioendothelioma/Hemangioma
- a.k.a. infantile hepatic hemangioma
- Vascular neoplasms most common liver tumor in neonates
  - Account for ˜ 60% of neonatal liver tumors
- Hemangioendothelioma more often symptomatic than cavernous hemangioma
  - Symptoms include abdominal distension, hepatomegaly, congestive heart failure, and respiratory distress
  - Other symptoms: Consumptive coagulopathy (Kasabach-Merritt syndrome) and rupture with intraperitoneal hemorrhage
  - Can be associated with hypothyroidism
  - ˜ 50% have cutaneous hemangiomas
- Large lesions have peripheral nodular enhancement on CT and MR
- Multiple lesions may be present
- Celiac and hepatic arteries often enlarged
- Angiosarcoma and choriocarcinoma can have similar appearance
  - Tumor markers (AFP and β-HCG) and follow-up imaging help confirm diagnosis
- Lesions should regress with age
  - Symptomatic lesions treated with medical or surgical therapy
- Hint: High-output heart failure with liver mass
Metastases
- More common than primary hepatic malignancies
- Neuroblastoma most common primary tumor to metastasize to liver
  - Stage 4S neuroblastoma can have diffuse hepatic infiltration
- Leukemia and Wilms tumor are next most common
- Rare metastases include yolk sac tumor, rhabdomyosarcoma, and rhabdoid tumor
- Hint: Known malignancy (i.e., neuroblastoma or Wilms tumor) with solitary or multiple liver masses
Hepatoblastoma
- < 10% occur in neonatal period
- Associated with hemihypertrophy, Beckwith-Wiedemann, trisomy 18, familial adenomatous polyposis coli, fetal alcohol syndrome, and extreme prematurity
- Differences in neonates compared to typical age range (0.5-3 years)
  - Worse prognosis
  - Metastases occur earlier and are often systemic
  - Fetal circulation allows metastases to bypass lungs
  - Do not produce excessive AFP
  - Tumor rupture can occur during labor/birth
- Hint: Liver mass in patient < 2 years old containing internal calcification
Mesenchymal Hamartoma
- 2nd most common benign hepatic mass
- Typically diagnosed in 1st 2 years of life
- Usually presents as palpable right upper quadrant mass
  - Most common in right lobe (75%)
  - AFP may be moderately elevated
- Multiloculated cystic mass
  - Mixed cystic and solid
  - Multiple tiny cysts may appear solid
  - On US, septae of cysts may be mobile
  - Large portal vein branch may feed mass
  - Calcification uncommon
- May ↑ in size over 1st few months
- Reports of malignant transformation to undifferentiated embryonal sarcoma
  - Treatment is complete excision

Helpful Clues for Less Common Diagnoses

Unilocular Cyst
- Usually simple cyst
  - No connection to biliary system
  - Hepatic scintigraphy (DISIDA) can prove cyst does not contain bile
- Often asymptomatic and requires no intervention
Choledochal Cyst
- Infantile type (patients < 1 year old)
  - Thought to have different etiology than childhood type
  - Presents with jaundice, vomiting, acholic stool, and hepatomegaly
  - Associated with biliary atresia in 44%
- Todani type 1 cyst most common
- Associated with ductal and vascular anomalies
  - Anomalous hepatic arteries, accessory hepatic ducts, and primary duct strictures
- US is good screening test
  - Cyst usually in subhepatic region or porta hepatis
  - Distinct from gallbladder
  - Anechoic, thin walled, with round, tubular, or teardrop shape
- MRCP or cholangiogram
  - Useful for showing connection of cyst to biliary system
  - Can see intra- or extrahepatic ductal abnormalities
- Treated with excision
  - ↓ risk of malignant degeneration if diagnosed before age 10

Helpful Clues for Rare Diagnoses

Abscess
- In neonates, most small and multiple
  - Solitary abscess accounts for 30%
- Risks include umbilical venous catheter, sepsis, and necrotizing enterocolitis requiring surgery
- Other risks: Immunodeficiencies, long-term parenteral nutrition, and prematurity
- S. aureus and gram-negative enteric bacteria most common organisms
Angiosarcoma
- a.k.a. hemangioendothelioma, type 2
- Few cases of diagnosis before age 1
- Looks like hemangioendothelioma
  - Continued growth after treatment should raise suspicion