Benign and Malignant Pediatric Liver Masses: Radiologic-Pathologic Update from the Pediatric LI-RADS Working Group

Primary pediatric liver tumors are uncommon but not rare, and they have clinical effects that range from self-limited to life-threatening. Although malignant liver tumors are more common than benign lesions in children, they comprise only 1%-2% of all pediatric malignancies. The combination of low incidence and variable outcomes can add uncertainty to interpretation. The authors review the most common pediatric liver lesions, both benign and malignant. Some lesions such as hemangioma, mesenchymal hamartoma, hepatoblastoma, and undifferentiated embryonal sarcoma of the liver are exclusively pediatric diseases. Others such as focal nodular hyperplasia, hepatocellular adenoma, hepatocellular carcinoma, and fibrolamellar carcinoma are well known in adult radiologic practices, but children may present and be treated differently. The patient's age at tumor development can help to narrow the differential diagnosis. An understanding of the underlying abnormality and its correlation to imaging findings also improves diagnostic confidence. MRI with hepatobiliary contrast agents may help to diagnose focal nodular hyperplasia by demonstrating contrast material retention in its functioning hepatocytes, but certain adenomas, well-differentiated malignancies, and even hemangiomas may show some degree of contrast material retention as well. Contrast-enhanced US can help to distinguish liver tumors based on temporal patterns of enhancement, but continued work shows overlap and exceptions that should be kept in mind. This review is aimed to update and review the current understanding of the most common pediatric liver tumors. ^©RSNA, 2025 Supplemental material is available for this article.