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Hepatoblastoma is the most common primary malignant liver tumor in children under four years of age who usually present with painless abdominal mass and raised AFP. It is tumor of embryonic origin.
Most cases are seen during the first 18 months of life and diagnosis in adulthood is exceedingly rare. Occasionally the tumor may be diagnosed antenatally 2. There is a recognized slight male preponderance with a M:F ratio of up to ≈3:2. There may also be predilection towards the right lobe of the liver.
Most children present with abdominal distension or an asymptomatic palpable abdominal mass. However, other presenting symptoms include 1:
- abdominal pain
- back pain
- pseudo precocious puberty (due to chronic GnRH secretion)
Macroscopically hepatoblastomas are usually relatively well circumscribed large masses, usually single, with heterogeneous cut surface 10.
Histological classification of hepatoblastoma is complicated with multiple subtypes identified. The notable subtypes include:
epithelial: most common
- fetal: best prognosis
- small cell undifferentiated: worst prognosis
- mixed type: epithelial and mesenchymal. Calcifications are more common in mixed type
It is important to note that with the possible exception of small cell undifferentiated subtype, prognosis is independent of histology when adjusted for stage gender and age 10.
For full classification please refer to hepatoblastoma histological classification.
Most hepatoblastomas are seen sporadically, however, it has been known to be associated with:
- Beckwith-Wiedemann syndrome 1
- hemihypertrophy: seen in 2% of patients with hepatoblastoma 1
- familial adenomatosis polyposis 3,5
- fetal alcohol syndrome 6
- prematurity and low fetal birth weight 1,6
- Gardner syndrome 5
- glycogen storage disease
- biliary atresia 1-2
Serum alpha fetoprotein (AFP) levels are frequently elevated (90% of cases 6).
Refer to: hepatoblastoma staging.
Caval involvement often indicates unresectable disease.
Abdominal x-rays are nonspecific, typically demonstrating a right upper quadrant mass. Calcifications are visible in 10% of cases 1,4.
On ultrasound, hepatoblastomas appear as predominantly echogenic soft tissue mass. In larger tumors heterogeneity and variable echogenicity is common. Even when large, they tend to be relatively well defined 7. Intralesional calcifications may be visible as areas of shadowing 4,7.
Usually seen as a well defined heterogeneous mass, which is usually hypoattenuating compared to surrounding liver 11. Frequently there are areas of necrosis and hemorrhage. Chunky, dense calcifications may be seen in approximately 40% of cases 11.
CT is also able to evaluate the lungs for metastases and for nodal enlargement.
MRI is superior to CT in defining tumor margins, vessel involvement and adenopathy 1.
- T1: generally hypointense
- T1 C+ (Gd): can show heterogeneous enhancement
- generally hyperintense compared to liver
- areas of necrosis and hemorrhage are common
- tend to be hypervascular
Treatment and prognosis
Surgical resection is the treatment of choice although preoperative chemotherapy may be used to reduce tumor bulk. Chemotherapy is also employed in following surgical resections. If the tumor is resectable then liver transplantation provides a cure, as long as no metastatic disease is present. The lungs are a relatively frequent site of metastases.
Overall there is 65-70% long-term survival 10, however, prognosis depends on staging:
- stage I: can expect very good long-term survival, of up to 100% with combined chemotherapy and surgery 8,12
- stage II: 75-80%
- stage III: 65%
- stage IV: 0-27% 10
General imaging differential considerations include:
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- 2. Woodward PJ, Sohaey R, Kennedy A et-al. From the archives of the AFIP: a comprehensive review of fetal tumors with pathologic correlation. Radiographics. 25 (1): 215-42. doi:10.1148/rg.251045156 - Pubmed citation
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- 7. Gubernick JA, Rosenberg HK, Ilaslan H et-al. US approach to jaundice in infants and children. Radiographics. 20 (1): 173-95. Radiographics (full text) - Pubmed citation
- 8. Russo P, Ruchelli ED, Piccoli DA. Pathology of pediatric gastrointestinal and liver disease. Springer Verlag. (2004) ISBN:0387406549. Read it at Google Books - Find it at Amazon
- 9. Kleinman RE. Walker's pediatric gastrointestinal disease, physiology, diagnosis, management. B.C. Decker. (2008) ISBN:1550093649. Read it at Google Books - Find it at Amazon
- 10. Suchy FJ, Sokol RJ, Balistreri WF. Liver disease in children. Lippincott Williams & Wilkins. (2001) ISBN:0781720982. Read it at Google Books - Find it at Amazon
- 11. King SJ, Babyn PS, Greenberg ML et-al. Value of CT in determining the resectability of hepatoblastoma before and after chemotherapy. AJR Am J Roentgenol. 1993;160 (4): 793-8. AJR Am J Roentgenol (abstract) - Pubmed citation
- 12. McGahan JP, Goldberg BB. Diagnostic ultrasound. Informa Health Care. (2008) ISBN:1420069780. Read it at Google Books - Find it at Amazon