Caroli disease in a 23-month-old boy: a rare paediatric presentation with an inconclusive cystic renal phenotype

Caroli disease is a ductal plate malformation defined by non-obstructive, communicating dilatation of the intrahepatic bile ducts without congenital hepatic fibrosis; when fibrosis is present, the condition is termed Caroli syndrome. We report the case of a 23-month-old boy who presented with hepatomegaly and jaundice. Abdominal ultrasound showed an enlarged liver with saccular cystic dilatation of the intrahepatic bile ducts and bilaterally enlarged kidneys with poor corticomedullary differentiation, prompting further cross-sectional evaluation. Magnetic resonance cholangiopancreatography confirmed non-obstructive, communicating intrahepatic bile duct dilatation consistent with Caroli disease, while renal imaging revealed a diffuse bilateral microcystic pattern with cortical thinning, most consistent with medullary sponge kidney. Imaging was thus central both to establishing the hepatic diagnosis and to characterizing the associated renal phenotype, sparing the child invasive investigation. This case illustrates that a hepatic ductal plate malformation may present in early childhood and unmask an otherwise silent renal cystic phenotype, and adds to the limited pediatric reports of this association.