Tumors of the Digestive System

Tissue from the alimentary canal, the hepatobiliary system, and the pancreas accounts for a significant portion of the day-to-day surgical pathology material in most diagnostic pathology laboratories. While many of the tumors encountered in these specimens are microscopically identical to homonymous tumors in other parts of the body and are graded similarly, some are unique to the gastrointestinal system. This chapter reviews the grading of the most common neoplasms of the digestive system. Several grading systems exist. In this chapter, we essentially adhere to the schemas agreed upon at the editorial and consensus conference of the International Agency of Research for Cancer (Lyon) December 2009 and published as the World Health Organization (WHO) Classification of Tumours of the Digestive System (Bosman et al. 2010).