Adenomyoma of the distal common bile duct demonstrated by endoscopic ultrasound: A case report and review of the literature

BACKGROUND: Adenomyomatous hyperplasia of the distal common bile duct (CBD) is very rare, with only scarce case reports in the literature. Diagnosis is usually based on imaging findings, and endoscopic biopsy is very difficult before operation. It is believed that adenomyomatous hyperplasia has little or no risk of malignant transformation. CASE SUMMARY: A 68-year-old woman with abdominal pain in the right upper quadrant was referred to our hospital. Abdominal ultrasonography in the emergency ward revealed acute cholecystitis and dilated CBD. Laboratory findings showed elevated levels of transaminases, phosphatase, and γ-glutamyltranspeptidase. Pharmaceutical treatment for 3 d did not relieve the symptoms. Magnetic resonance cholangiopancreatography (MRCP) and computed tomography (CT) showed proximal bile duct dilatation but could not identify the cause. Endoscopic ultrasonography (EUS) demonstrated a mixed echogenic mass in the distal CBD. During surgery, a firm mass was found in the distal CBD and the Whipple procedure was performed with the initial concern of malignancy. Histology showed diffuse adenomyomatous hyperplasia. CONCLUSION: EUS may be a useful choice to diagnose adenomyoma of the distal CBD before operation, especially in patients with ambiguous MRCP/CT findings.