Pediatric Primary Hepatic Tumors: Diagnostic Considerations

Abstract

The liver is the third most common site of abdominal tumors in children. This review article aims to summarize current evidence surrounding identification and diagnosis of primary hepatic tumors in the pediatric population based upon clinical presentation, epidemiology, and risk factors as well as classical imaging, histopathological, and molecular diagnostic findings. Readers will be able to recognize the features and distinguish between benign and malignant hepatic tumors within different age groups.

Keywords: angiosarcoma; focal nodular hyperplasia; hepatic adenoma; hepatoblastoma; hepatocellular carcinoma; infantile hepatic hemangioma; liver tumor; malignant rhabdoid tumor; mesenchymal hamartoma; pediatric; undifferentiated embryonal sarcoma.

Figure 1

CT and MRI Imaging of Unifocal Hemangioma. (A) CT: The liver is remarkable for a well-circumscribed rounded lesion in the left lobe of the liver. This measures approximately 3.3 cm in anterior–posterior dimension by 3.1 cm in transverse dimension by 2.4 cm in craniocaudal dimension. There is intense peripheral enhancement with mixed enhancement of the internal portion of this lesion. (B) MRI: A large T2 hyperintense well circumscribed mass is seen in left lobe within segment 2 and 3 of the liver measuring 2.9 × 2.9 × 2.5 cm in anterior-posterior, transverse and craniocaudal dimensions. It demonstrates peripheral nodular enhancement with centripetal contrast filling.

Figure 2

CT Imaging of Multifocal Hemangioma. There are numerous foci of intense enhancement on early postcontrast imaging throughout the liver, which become isointense to surrounding liver parenchyma on delayed imaging.

Figure 3

Hepatic hemangioma (hematoxylin & eosin (H&E), 10× magnification). Vascular channels lined by benign-appearing endothelial cells, with surrounding hepatic parenchyma.

Figure 4

Mesenchymal hamartoma (H&E, 4× magnification). Mixture of epithelial and stromal elements, with interspersed hepatic parenchyma. The epithelial component consists of disorganized bland ductal structures, and the stromal component includes spindle cells, set in a loose myxoid background.

Figure 5

CT Imaging of Hepatoblastoma. There is a lobulated heterogeneous mass involving the fifth and sixth segments of the right lobe, which also contains well-defined rounded hypoattenuating areas. No calcification can be seen. The mass extends inferiorly from the right lobe of the liver as well as extending lateral and anterior to the liver at its superior aspect. The mass measures approximately 21.7 cm in greatest sagittal dimension and 10.6 cm in greatest transverse dimension and 10.7 cm in greatest AP dimension. Superiorly, the mass appears to displace the anterolateral aspect of the liver posterior and medially and inferiorly, the mass displaces bowel posteriorly and medially.

Figure 6

Hepatoblastoma (H&E, 10× magnification). Mixed embryonal (left) and fetal hepatoblastoma. The embryonal component demonstrates a higher nuclear-to-cytoplasmic (N:C) ratio and forms rosette-like structures, while the fetal component recapitulates the appearance of fetal hepatocytes.

Figure 7

Malignant rhabdoid tumor (H&E, 20× magnification). Typical rhabdoid cells, with eccentric nuclei with prominent nucleoli, and eosinophilic cytoplasm, with discohesive architecture.

Figure 8

Hepatic adenoma (H&E, 4× magnification). Hepatic parenchyma with no cytologic atypia and effacement of normal lobular architecture, with lack of portal tracts.

Figure 9

Focal nodular hyperplasia (H&E, 4× magnification). Nodular hepatic parenchyma with bile ductular proliferation and central scar containing abnormal blood vessels.

Figure 10

CT Imaging of Hepatocellular Carcinoma. Irregular heterogeneously enhancing mass is present in the right hepatic lobe, extending exophytically, laterally, and inferiorly from the liver surface, measuring up to 9.9 × 9.0 cm in maximum transaxial diameters with central hypoattenuation, suggesting necrosis. There is nodular extension along the peritoneal surface lateral to the right hepatic lobe, as well as more anteriorly.

Figure 11

Conventional hepatocellular carcinoma (H&E, 10× magnification). Malignant proliferation of hepatocytes, with pleomorphism, large, prominent nucleoli, and abundant mitotic figures, including atypical forms.

Figure 12

Fibrolamellar type hepatocellular carcinoma (H&E, 10×). Malignant proliferation of hepatocytes with abundant, granular eosinophilic cytoplasm with prominent nucleoli, set in a fibrotic stroma.

Figure 13

Undifferentiated embryonal sarcoma (H&E, 10× magnification). Sheets of highly pleomorphic cells with abundant mitotic figures, set in a myxoid stroma.