Accessory liver lobe: an uncommon abdominal mass mimicker

Heterotopic hepatic tissue is a rare development anomaly, exhibiting diverse forms and locations. We present a case report of an asymptomatic woman in her 40s who had an 8 cm mass in the left hypochondrium detected on routine ultrasound, which was initially suspected to be a tumour. Further investigation revealed that the mass had a similar enhancement to the liver on gadoxetate disodium-enhanced MRI and presented a connection with the original liver via vascular pedicle, favouring the diagnosis of accessory liver lobe (ALL). Accurate differentiation of ALL from other abdominal masses poses a diagnostic challenge, potentially leading to misdiagnosis of malignant tumours and unnecessary interventions. Although usually small and asymptomatic, rarely they can present with acute complications, and cross-sectional techniques play an important role in enabling early diagnosis and management. Therefore, radiologists must raise awareness regarding ALL, their imagological findings, and diagnostic pathways, and understand potential associated complications.