A cystic lesion adjacent to the cystic duct diagnosed as ectopic thyroid tissue: a laparoscopic case report

Jingnan Xue^1*Longhao Zhang²Xiaohai Wu¹Xiaoli He¹Nanzi Xie¹Kai Zhou^1*Gang Xie^1*

• ¹Anshun City People's Hospital, Anshun, China
• ²Peking Union Medical College Hospital Department of Liver Surgery, Beijing, China

Ectopic thyroid tissue is an uncommon developmental anomaly, and involvement of the hepatobiliary region—particularly near the gallbladder neck or cystic duct—is extremely rare. Such lesions may mimic primary biliary or gallbladder masses, creating diagnostic and therapeutic uncertainty. We report a 50-year-old woman with a 2-year history of intermittent right upper quadrant abdominal pain. Contrast-enhanced CT demonstrated a well-defined hyperdense lesion at the hepatic hilum adjacent to the gallbladder neck, measuring 22 × 14 mm (∼80 HU on non-contrast; 119 HU arterial; 104 HU venous), with indistinct borders from the gallbladder. A biliary or gallbladder-associated tumor could not be excluded, and further evaluation with MRI and PET-CT was recommended. The patient declined additional imaging due to financial constraints and strongly requested operative management. Laparoscopic cholecystectomy with en bloc resection of the hilar lesion was performed. Intraoperative frozen-section analysis and final histopathology revealed benign ectopic thyroid tissue composed of mature, well-differentiated thyroid follicles without atypia. Postoperative thyroid ultrasound showed a normal orthotopic thyroid gland. The patient recovered uneventfully and remained symptom-free at follow-up. Ectopic thyroid tissue adjacent to the gallbladder neck is an exceptionally rare cause of a hilar mass. Surgeons should consider this entity in the differential diagnosis of gallbladder neck or porta hepatis lesions of uncertain origin and rely on histopathology to guide appropriate, conservative management.