SpyGlass-assisted diagnosis of biliary tract invasion by diffuse large B-cell lymphoma: a case report

Abstract Background Diffuse large B-cell lymphoma (DLBCL) of the common bile duct (CBD) is exceedingly rare and mimics cholangiocarcinoma or choledocholithiasis, delaying diagnosis. Endoscopic Retrograde Cholangiopancreatography (ERCP) brush cytology offers limited sensitivity for indeterminate biliary strictures. SpyGlass cholangioscopy enables direct visualization and targeted biopsy with higher diagnostic yield in this case. This case illustrates its role in diagnosing biliary lymphoma and uses gene rearrangement analysis to assess clonal relatedness between synchronous gastric and biliary lesions. Case presentation A 59-year-old male presented with fever, jaundice, and epigastric pain. Laboratory tests confirmed obstructive jaundice and acute pancreatitis. Imaging revealed a distal CBD stricture, hepatic lesions, and lymphadenopathy. Gastroscopy identified gastric DLBCL. Emergency ERCP with biliary stenting relieved obstruction. SpyGlass cholangioscopy visualized a 3/4 circumferential distal CBD mass; targeted biopsy confirmed DLBCL (CD20+, CD79a+) on histology and immunohistochemistry. The patient had a history of untreated duodenal follicular lymphoma, suggesting transformation. Gene rearrangement analysis demonstrated identical clonal origin of gastric and biliary lesions, with an additional rearrangement in the biliary lesion. Conclusion This case describes the role of SpyGlass cholangioscopy in diagnosing biliary lymphoma. Gene rearrangement analysis confirmed a shared clonal origin of the gastric and biliary lesions, although an additional immunoglobulin rearrangement detected in the biliary lesion remains of uncertain significance.