Pediatric Hepatic Cystic Lesions: Differential Diagnosis and Multimodality Imaging Approach.

When a pediatric hepatic cystic lesion is identified at imaging, the differential diagnosis may be broad, including developmental, infectious, neoplastic, and posttraumatic or iatrogenic causes. The location of a cystic lesion and its number, size, composition, and relationship to the biliary system are features that help in narrowing the differential diagnosis. An incidentally detected simple hepatic cyst is the most commonly encountered. Ciliated foregut cysts are typically located in hepatic segment IVa. The presence of multiple cysts should raise suspicion for fibropolycystic liver disease, a group of related lesions-including biliary hamartoma and choledochal cyst-caused by abnormal embryologic development of the ductal plate. Communication of the cystic lesion with the biliary tree can confirm the diagnosis of choledochal cyst. In a neonate with jaundice, a cystic lesion at the porta hepatis should raise suspicion for choledochal cyst versus cystic biliary atresia. Hepatic abscess can appear cystlike, though typically with internal contents. In an immunocompromised child, multiple cystlike lesions should raise concern for fungal microabscesses. A complex cystic mass in a young child should raise suspicion for mesenchymal hamartoma, which can evolve into undifferentiated embryonal sarcoma if untreated. Hepatic hematoma and biloma can appear cystlike in children with a history of trauma or recent intervention. In neonates with an umbilical vein catheter (UVC), an intrahepatic cyst along the course of the UVC should raise concern for infusate extravasation. Familiarity with imaging findings and clinical features is essential for achieving accurate diagnosis of pediatric hepatic cystic lesions, which in turn can guide appropriate clinical management. RSNA, 2022.