Neoplastic precursors of the gallbladder and extrahepatic biliary system.

Premalignant lesions of the gallbladder and extrahepatic bile ducts have been poorly studied compared with their counterparts in the remainder of the gastrointestinal tract. Some of the problematic issues, such as the subjectivity of grading and determination of the relative risk of cancer, are challenging. Although the understanding of the biology of these lesions has improved in the past several years, there are still many issues that can only be addressed by close collaboration between gastroenterologists, radiologists, hepatobiliary surgeons, oncologists, and pathologists.