Background : Mucinous cystadenoma neoplasm (MCN) or also known as hepatobiliary cystadenoma is a rare benign hepatic tumor that comprises approximately <5% of cystic mass in adult. This kind of tumor is defined by WHO as a cyst-forming epithelial neoplasm with female sex predominance. This case report aims to discuss a 23-year-old- male patient presenting with a rare case of biliary mucinous cystic neoplasm encountered at Ilocos Training and Regional Medical Center, City of San Fernando, La Union.

Methods : A case report providing an overview of the diagnosis and management of cystic lesion in the liver. Since, Mucinous Cystadenoma Neoplasm (MCN) is a type of cystic liver mass wherein appropriate management with complete surgical resection with negative margins is recommended given the risk of recurrence and its malignant transformation.

Results : We present a 23-year-old male patient complaining of vague abdominal pain wherein whole abdomen Ultrasound and whole abdominal CT scan with Triphasic were done revealing a right hepatic lobe complex cystic mass lesion measuring 12 x 1 x 6 cm suggested a probable infectious versus inflammatory process or cystic tumor such as atypical hemangioma. As such consideration, to prevent bleeding, patient initially underwent Open Core needle Biopsy with intraoperative ultrasound. Histopathology reveals Biliary Cystadenoma. Hence, Right Hepatectomy was done. Patient was then discharged after post op day 8. Three (3) months post operatively, patient remains asymptomatic.

Conclusions : Most often, this type of cystic neoplasm have tendency of recurrence approximately 90% when the resection is incomplete and malignant transformation as 20% may become invasive. Thus, appropriate management with complete surgical resection with negative margins is recommended. Patient underwent formal right hepatectomy and remains asymptomatic and recurrence of cystic mass since discharged.