Pathologically confirmed complete remission after neoadjuvant chemotherapy in patients with advanced intrapancreatic cholangiocarcinoma following robot-assisted excision of choledochal cyst: A case report.

The occurrence of cholangiocarcinoma following choledochal cyst excision is a rare clinical entity. In cases with extensive lymphadenopathy, where poor oncologic prognosis is anticipated, immune checkpoint inhibitors have recently shown promise as a therapeutic approach in biliary tract cancer. We describe a case involving successful minimally invasive pylorus-preserving pancreaticoduodenectomy in this unusual patient, following neoadjuvant immune chemotherapy. A 44-year-old female, who had previously undergone bile duct excision for choledochal cyst on November 28, 2022, presented with abdominal pain in July 2024. Imaging revealed an 8-cm mass in the pancreatic head, with multiple metastatic lymph nodes noted in the epigastrium, mesentery, retroperitoneum, and both common iliac chains. Endoscopic ultrasound-guided biopsy identified atypical cells with necrosis suggestive of poorly differentiated carcinoma, but immunohistochemistry did not confirm pancreatic origin. Positron emission tomography-computed tomography revealed absence of additional primary malignancy, though it showed multiple enlarged lymph nodes and findings indicative of possible peritoneal seeding. Considering the patient's prior history of choledochal cyst resection and extensive perihilar lymphadenopathy, a diagnosis of cholangiocarcinoma was favored. Neoadjuvant chemoimmunotherapy with durvalumab, gemcitabine, and cisplatin was administered across 11 cycles. Subsequent imaging demonstrated significant tumor regression, prompting surgical exploration on April 11, 2025. Intraoperatively, extensive adhesions surrounding the hepaticojejunostomy and pancreas were encountered. Pancreaticoduodenectomy was completed utilizing the pre-existing Roux limb for pancreaticojejunostomy. Frozen section analysis of the peritoneum and mesentery was negative for malignancy. Final histopathology confirmed complete remission. This case highlights the potential feasibility and safety of minimally invasive surgery in this rare clinical scenario.