Adenosquamous Carcinoma of Lower Extrahepatic Biliary Tract: A case report

Adenosquamous carcinoma, consisting of adenocarcinoma and squamous cell carcinoma, rarely occurs in the extrahepatic bile duct. Due to nonspecific imaging findings, preoperative diagnosis of adenosquamous carcinoma depends exclusively on brushing cytology or biopsy performed under endoscopic retrograde cholangiopancreatography (ERCP). However, correct diagnosis before surgical resection is challenging in some patients. Here, we report the case of a patient with adenosquamous carcinoma in the lower extrahepatic bile tract diagnosed using brushing cytology under ERCP.