Introduction Brushing cytology and fine-needle aspiration (FNA) are used to sample lesions in the biliary tract and pancreas. Endobiliary brushing is currently the preferred method of sampling the pancreatobiliary system in patients with a stricture or obstruction without an associated…
Introduction Cancer is fundamentally a genetic disease caused by inherited germline variants coupled with the accumulation of somatic mutations in oncogenes and tumor suppressor genes. Some patients inherit gene mutations that predispose them to cancer, while others acquire all alterations…
Introduction Disorders of the biliary tract affect a significant portion of the world’s population. More than 95% of biliary tract disease is attributable to cholecystitis and cholelithiasis (i.e., gallstones). It is estimated that about 20 million persons in the United…
Introduction Normal Histology Microscopically, the pancreas is composed of epithelium (acini, islets, and ducts), connective tissue, and lymphoid tissue. These components may be variably present within any individual pancreatic biopsy, depending on the location and adequacy of the tissue sample.…
Embryology and Anatomy of the Anus and Anal Canal The anal canal forms during the fourth to seventh weeks of gestation after partitioning of the cloaca into the ventral urogenital membrane and dorsal membrane. The epithelium of the superior two-thirds…
Introduction In 55% to 75% of gastrointestinal (GI) lymphomas, the stomach is the primary site. Lymphoma accounts for 1% to 7% of all gastric malignancies. , Diffuse large B-cell lymphoma and extranodal marginal-zone lymphoma of mucosa-associated lymphoid tissue (MALT lymphoma)…
Introduction Although epithelial neoplasms predominate in the tubal gut, a variety of mesenchymal neoplasms may originate from or secondarily involve the gastrointestinal (GI) tract. Given the rarity of these lesions and the fact that many have overlapping histological features, accurate…
Acknowledgment The authors are indebted to Dr. Hulya Sahin Ozkan, Dr. Kerem Ozcan, and Ms. Rhonda Everett for their extensive contributions in the preparation of this chapter. Neuroendocrine Cell System of the Gastrointestinal Tract Neuroendocrine cells in the gastrointestinal (GI)…
Mucinous Epithelial Tumors The classification of appendiceal epithelial tumors is shown in Box 28.1 . The classification, nomenclature, and histological criteria of mucinous epithelial tumors in the appendix have been the source of considerable controversy. In particular, mucinous epithelial tumors…
Introduction The most common neoplasms of the large intestine are adenomas, conventional or serrated in type (see Chapter 22 ). Adenomas are the precursor of most primary malignant epithelial neoplasms of the large intestine. Although abundant clinical, morphological, and genetic…