Adenosquamous Carcinoma of the Extrahepatic Bile Duct.

Most malignant tumors arising from the biliary tract are adenocarcinomas. Adenosquamous carcinoma is an uncommon variant of extrahepatic bile duct cancer that is associated with more aggressive behavior than adenocarcinoma. A 58-year-old male presented with complaints of obstructive jaundice and dull aching pain in the abdomen. At his initial evaluation in another hospital, ultrasound of the abdomen and magnetic resonance cholangiopancreatography revealed common bile duct dilatation with an ill-defined lesion in the periampullary region. Endoscopic retrograde cholangiopancreatography showed infiltration of the ampulla. Biopsy specimen taken during stenting of the common bile duct suggested dysplasia. Because of recurrent jaundice, the patient was referred to our institution, and contrast-enhanced computed tomography (CT) of the abdomen showed a hypoenhancing lesion with ill-defined margins in the head of the pancreas. The patient underwent a Whipple procedure. Microscopic examination of the pancreaticoduodenectomy specimen showed an invasive adenosquamous tumor arising from the distal part of the common bile duct that infiltrated the body and head of the pancreas, involved the wall of the duodenum, and reached the duodenal mucosa. Morphologic diagnosis was supported by immunohistochemistry profile. Postoperative contrast-enhanced CT of the abdomen showed multiple enlarged mesenteric lymph nodes and multiple lesions in both lobes of the liver, suggestive of metastasis. The patient died 1 week after surgery. Because the clinical, pathologic, and prognostic characteristics of adenosquamous carcinoma are poorly known, early diagnosis of this rare entity is warranted for patient management.