Multimodal imaging features of pelvic ectopic liver combined with type I congenital extrahepatic portosystemic shunt (Abernethy malformation) in a child: a case report.

Objective: To investigate the multimodal imaging features, vascular anatomical characteristics, and clinical management strategies of pelvic ectopic liver combined with Type I congenital extrahepatic portosystemic shunt (Abernethy malformation) in a child, thereby enhancing the diagnostic and therapeutic understanding of this rare complex congenital anomaly. Methods: A retrospective analysis was conducted on the complete clinical and imaging data of a 12-year-old male pediatric patient. Multimodal imaging findings from ultrasound, magnetic resonance imaging (MRI), computed tomography angiography (CTA), and digital subtraction angiography (DSA) were integrated to systematically analyze the imaging manifestations of the lesion, the blood supply characteristics of the ectopic liver and portosystemic venous malformation, and the features of vascular anatomy. Results: The patient presented with a chief complaint of dysuria and urinary dribbling for one month. Multimodal imaging revealed an irregular soft tissue mass in the pelvic cavity, connected to the left hepatic lobe via a soft tissue pedicle. The enhancement pattern on contrast-enhanced imaging was identical to that of the orthotopic liver, consistent with the imaging features of pelvic ectopic liver. CTA three-dimensional vascular reconstruction and DSA demonstrated hypoplasia of the proper hepatic artery, with its left branch abnormally coursing inferiorly to supply the pelvic ectopic liver. The superior mesenteric vein drained directly into the inferior vena cava, with no opacification of the intrahepatic portal venous system, consistent with the imaging diagnosis of type I Abernethy malformation. To our knowledge, no similar case of pelvic ectopic liver combined with type I congenital extrahepatic portosystemic shunt has been reported globally. Following multidisciplinary consultation, a conservative management strategy of long-term imaging follow-up was adopted for the patient, with no surgical intervention planned at present, and liver transplantation reserved as a definitive treatment option in the event of severe long-term complications. Conclusion: Pelvic ectopic liver combined with type I congenital extrahepatic portosystemic shunt represents an extremely rare congenital composite hepatic vascular and visceral malformation in clinical practice. The multimodal imaging system integrating ultrasound, MRI, CTA, and DSA can accurately and comprehensively delineate the location, morphology, blood supply origin of the ectopic liver, and the anatomical details of the portosystemic venous malformation. It serves as a reliable imaging basis for the diagnosis, anatomical assessment, and long-term follow-up of this rare pediatric condition, and provides critical support for the formulation of individualized clinical treatment strategies.