High-grade neuroendocrine carcinomas of the gallbladder and bile duct: Report of four cases with pathological correlation.

The extrahepatic biliary system is one of the unusual locations of extrapulmonary neuroendocrine carcinoma. To our knowledge, there has been no report describing the imaging findings of this rare malignancy of the biliary tree. We report 3 large-cell neuroendocrine carcinomas and a small-cell carcinoma arising from the biliary system. Biliary tumors showing on computed tomography an aggressive invasion to the liver or extensive lymph node involvement should raise the suspicion of their being high-grade neuroendocrine tumors.