Hepatic and perihepatic cystic lesions may present with heterogeneous radiologic characteristics that overlap with neoplastic, infectious, and biliary etiologies, posing a diagnostic challenge in the context of biliary obstruction¹. We present the case of a 68-year-old woman who initially developed biliary colic and was diagnosed with chronic calculous cholecystitis and high-risk choledocholithiasis. CT scan demonstrated a choledochal stone at the intrapancreatic portion of the common bile duct, along with additional cholelithiasis.

ERCP was performed, revealing three filling defects measuring approximately 12 mm each. Complete ductal clearance was not achieved despite appropriate maneuvers and biliary stent was placed. Given the persistence of biliary obstruction, a magnetic resonance cholangiopancreatography study was obtained three days after ERCP. This demonstrated a large capsular lesion located in hepatic segment VIII, measuring 147 × 95 × 63 mm. Additionally, CA 19-9 was reported at 1366 U/mL, a finding that raised concern for a biliary or cystic neoplasm.²

Two weeks later, the patient was referred to our center for further evaluation. Endoscopic ultrasound revealed a well-defined, homogeneous hypoechoic mass exerting significant extrinsic compression on the gastric wall, measuring 121 × 77 mm. Because imaging alone could not provide a definitive diagnosis, a decision was made to perform fine-needle puncture using a 19-gauge needle.³

Puncture of the lesion resulted in immediate drainage of purulent material, establishing the diagnosis of a hepatic abscess. Given the volume of purulent content and the mass effect on adjacent structures, an endoscopic drainage strategy was selected. A 20 × 10-mm lumen-apposing metal stent (LAMS) was deployed under EUS guidance, achieving rapid and effective internal drainage.

Microbiologic evaluation confirmed infection with Escherichia coli. The patient completed targeted antibiotic therapy. Her clinical evolution was favorable, and a follow-up CT scan obtained one month after the procedure demonstrated near-complete resolution of the hepatic lesion. Subsequent ERCP and surgical gallbladder removal were performed.

This case illustrates the essential role of EUS in clarifying equivocal hepatobiliary lesions initially suspected to be neoplastic, and demonstrates the clinical effectiveness of LAMS-guided drainage as a minimally invasive therapy for large hepatic abscesses. The multidisciplinary evaluation and stepwise therapeutic decision-making allowed full patient recovery and resolution of both the abscess and the biliary obstruction.⁴