LAUSR

INTRODUCTION Biliary cystadenomas (BCAs) are rare benign tumors with malignant potential. They are most commonly found in middle-aged women and are quite infrequently reported in children. Even with advanced imaging, diagnosing and distinguishing BCA from other cystic liver lesions remain challenging. CASE PRESENTATION A 5-year-old boy was brought in by his parents to our hospital with abdominal swelling that had been persistent for a year, along with loss of appetite and weight loss. On examination, the abdomen was distended and dull on percussion. We considered mesenchymal hamartoma of the liver (MHL) as the top differential after an abdominal CT scan with contrast showed a multi-loculated cystic tumour. For both definitive diagnosis and therapy, the patient underwent exploratory laparotomy with excision of the cystic mass. Surprisingly, histopathology examination of the resected specimen revealed biliary mucinous cystadenoma (BCA). CONCLUSION Since conservative methods are associated with high recurrence rates, biliary mucinous cystic neoplasms require a high index of suspicion and should be handled with total surgical resection. In the post-operative phase, periodic surveillance imaging is recommended due to the risk of recurrence and malignant transformation.