Preoperative Diagnosis of the Bile Duct Traumatic Neuroma by Endoscopic Ultrasound‐guided Tissue Acquisition: A Case Report

ABSTRACT

Traumatic neuroma of the cystic duct stump is a rare benign lesion that may mimic biliary malignancy, making preoperative diagnosis challenging. We report a case of an enhancing lesion at the cystic duct stump after cholecystectomy that was diagnosed by endoscopic ultrasound‐guided tissue acquisition (EUS‐TA). Imaging studies revealed an 8‐mm enhancing nodule at the cystic duct stump, and endoscopic retrograde cholangiopancreatography showed a unilateral filling defect at the corresponding site. Peroral cholangioscopy demonstrated smooth mucosa without irregular vessels, suggesting a submucosal lesion rather than mucosal malignancy. EUS revealed a well‐demarcated, homogeneous hypoechoic mass immediately distal to the origin of the remnant cystic duct. EUS‐TA using a 22‐gauge needle enabled TA from the lesion. Histopathological examination showed proliferation of spindle‐shaped cells with wavy nuclei, and immunohistochemical staining was positive for S‐100 protein, confirming the diagnosis of traumatic neuroma. No procedure‐related adverse events occurred, and unnecessary surgical resection was avoided. EUS‐TA may facilitate preoperative diagnosis of cystic duct stump traumatic neuroma and help guide appropriate management.