Discussion: Pediatric Liver Lesions
Abscess
Bacterial and fungal abscesses are most often seen in immunocompromised patients. Bacterial abscesses are most often E. coli and less frequently Streptococcus or Listeria. Fungal abscesses are most frequently secondary to Candida; Aspergillus, mucormycosis, and Cryptococcus are also etiologic agents. Hydatid disease is rare in the US, but is a cause of hepatic abscess. Amebiasis is another rare cause of hepatic abscess; this most often effects children less than 3 years.
Benign Neoplasms
Infantile hemangioendothelioma – most common liver tumor in the first 6 months of life. Can cause CHF, secondary to shunting, and thrombocytopenia. Usually multilocular and shows early peripheral and delayed central enhancement on contrasted studies.
Mesenchymal hamartoma – rare benign lesion, multicystic mass. These are usually seen in children less than 2 years old; median age is 11 months.
Focal nodular hyperplasia – uncommon in pediatrics but does occur. 8% of FNH are in patients less than 15 years old. Predominately seen in females, 4:1. 80% are solitary.
Malignant Neoplasms
Malignant lesions in the liver are more common than the benign lesions in pediatrics. However, primary hepatic tumors are uncommon, accounting for 0.5 to 2.0% of all pediatric neoplasms.
Hepatoblastoma – Most common primary hepatic tumor in childhood. Most patients are less than 5 years old at presentation with the majority less than 2 yrs. This tumor is not related to chronic liver disease, but is associated with Beckwith-Weidemann syndrome, maternal use of clomiphene citrate, familial adenomatous polyposis, occurance in siblings, and trisomy 18. alpha fetoprotein is usually elevated and some hepatoblastomas produce HCG. Hepatoblastomas are usually single.
Hepatocellular Carcinoma – Hepatocellular carcinoma (HCC) is an aggressive hepatic neoplasm that most commonly affects adults. In pediatrics, HCC is usually seen in the age range of 5 to 15 years. There is a definite association with chronic liver disease, ie cirrhosis, biliary atresia, hepatitis, and glycogen storage disease. However, most commonly, there is no known liver disease at the time of diagnosis. May be solitary, multifocal, or diffuse. Alpha fetoprotein is elevated in 50% of patients. Fibrolamellar carcinoma is a histologically distinct subtype with a better prognosis.Although surgical resection remains the mainstay of curative therapy, adjunctive chemotherapeutic and radiotherapeutic strategies are also helpful.
Rhabdomyosarcoma of the biliary tree – Rare tumor usually in patients less than 5 years old. Patients often present with jaundice.
Undifferentiated embryonal cell sarcoma – Also rare, and primarily seen in older patients
Metastatic disease – Most common metastatic lesions to the liver are neuroblastoma, Wilms tumor, and lymphoma and leukemia.
