Diagnosis of rare signet-ring cell carcinoma of the bile duct by endoscopic ultrasonography combined with a peroral direct cholangioscopy biopsy.

Biliary signet-ring cell carcinoma is a rare malignant tumor of the biliary tract. signet-ring cell carcinoma often occurs in the gastrointestinal tract. In this case, we can intuitively see the location, shape and scope of the tumor through endoscopic ultrasonography (EUS) combined with a peroral direct choledochoscope. Through the direct view biopsy technology, the tumor tissue in the biliary tract can be accurately sampled, providing a precise plan for the follow-up treatment of patients.