A Rare Case of a Pedunculated Accessory Liver Lobe Arising from Segment 3: A Radiological Insight

Accessory liver lobes (ALLs) are rare congenital anatomical variations that may mimic pathological conditions, leading to diagnostic challenges. Among these, pedunculated ALLs are exceptionally uncommon. We report a rare case of a pedunculated ALL arising from segment 3 of the liver in a 45-year-old male patient with no known medical history. The lobe was incidentally detected on contrast-enhanced abdominal computed tomography performed for an unrelated indication. Imaging revealed a well-defined hepatic structure extending from the portal hilum toward the lesser omentum, maintaining continuity with the liver parenchyma. ALLs have been classified into different subtypes based on their anatomical connection to the liver. Their presence can lead to diagnostic confusion, as they may mimic hepatic, retroperitoneal, or even thoracic masses. While most cases are asymptomatic, complications such as torsion, rupture, or hemorrhage have been reported. Advanced imaging techniques, including cross-sectional imaging, nuclear scintigraphy, and hepatobiliary-phase magnetic resonance imaging, can aid in diagnosis. In this case, the accessory lobe could have been misinterpreted as a papillary process of the caudate lobe. Recognition of ALLs is crucial to prevent unnecessary surgical interventions and misdiagnosis. Radiologists should be familiar with this rare anatomical variant to ensure accurate interpretation of imaging findings. To our knowledge, this is the first reported case of a pedunculated ALL arising from segment 3.