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Polyps of the Large Intestine

Introduction Large bowel screening programs have been shown to substantially reduce the incidence of colorectal carcinoma by identifying and removing premalignant polyps. Increased use of colonoscopy has led to an increase in the number of polyps encountered in daily pathology practice. Broadly speaking, the term polyp refers to any form of lesion that projects above the surrounding colonic mucosa. The vast majority of colorectal polyps are…

Polyps of the Small Intestine

Introduction Upper gastrointestinal (GI) endoscopy is routinely performed as part of the evaluation of patients with GI symptoms. Newer techniques such as double-balloon enteroscopy and capsule endoscopy also allow for complete visualization of the small intestine. Gastroenterologists may identify and sample a variety of polyps, nodules, excrescences, and subtle abnormalities in the mucosa during the course of the procedure that, before the endoscopic era, would have…

Polyps of the Stomach

Introduction Gastric polyps are identified in up to 6.3% upper gastrointestinal (GI) endoscopic procedures. They may develop as a result of epithelial or stromal cell hyperplasia, inflammation, ectopia, or neoplasia. This chapter classifies gastric polyps according to the predominant cell type (e.g., epithelial, lymphoid, mesenchymal) responsible for polyp growth ( Box 20.1 ). Epithelial polyps can also be categorized according to the epithelial compartment from which…

Polyps of the Esophagus

Introduction Most types of inflammatory lesions of the esophagus do not manifest as endoscopically recognizable polyps. They instead cause only a slight mucosal irregularity or surface erosion. In contrast, most neoplastic processes of the esophagus manifest clinically at an advanced pathological stage. Malignant tumors may form strictures, plaquelike masses, or deeply penetrating or fungating ulcers. Polyps, which are discrete, well-circumscribed luminal protrusions, are uncommon in the…

Inflammatory Disorders of the Appendix

Introduction The appendix is a vestigial organ without proven significant physiological function; however, it is subject to a host of clinically significant inflammatory disorders, some of which involve the appendix exclusively and others that are systemic. The vermiform appendix arises from the medial aspect of the cecum, inferior and posterior to the ileocecal orifice. It averages 8 cm long (range 2 to 20 cm) and 0.7…

Inflammatory Disorders of the Large Intestine

Approach To Evaluating Colitis Pathologists are asked to evaluate colorectal biopsy specimens for a variety of reasons, but often only a pattern of injury can be identified, at best. This evaluation is performed with the hope that a specific diagnosis can be rendered once appropriate clinical, radiological, and laboratory information is obtained. However, some forms of colitis, such as lymphocytic colitis, collagenous colitis, and ischemic colitis,…

Inflammatory Disorders of the Small Intestine

Disorders of Malabsorption Box 16.1 lists intestinal malabsorptive disorders by disease category. BOX 16.1 Intestinal Malabsorptive Disorders by Disease Category Autoimmunity Celiac disease Autoimmune enteropathy Hypersensitivity Protein allergy (milk, soy) Eosinophilic gastroenteritis Infection Tropical sprue Bacterial overgrowth/blind loop Other infections Nutritional deficiencies B 12 /folate deficiency Protein-calorie deficiency Zinc deficiency Iron deficiency Inherited/metabolic/malformation Microvillous inclusion disease Abetalipoproteinemia Primary intestinal lymphangiectasia Chronic granulomatous disease Disaccharide deficiencies Neoplastic/infiltrative…

Inflammatory Disorders of the Stomach

Historical Perspective In 1947, at the dawn of gastroscopy, Rudolf Schindler deemed gastritis “one of the most debated diseases of the human body” and predicted that its significance would be discussed “for some time to come.” From the mid-1800s, when Cruveiller exposed the inaccuracies of Broussais’s first descriptions of gastritis in autopsy material, to the early 20th century, the concept of gastritis as a disease had…

Inflammatory Disorders of the Esophagus

Introduction Inflammatory disorders of the esophagus are extremely common. Among the most common is gastroesophageal reflux disease (GERD), a chronic condition, affecting as many as 40% of people in the Western world. Because of the ease and frequent use of upper endoscopy for diagnosing gastrointestinal (GI) illnesses, biopsy specimens procured from esophageal mucosa to evaluate the presence or absence of inflammatory diseases—particularly GERD and its attendant…

Algorithmic Approach to Diagnosis of Inflammatory Disorders of the Gastrointestinal Tract

Introduction The conventional approach to teaching about inflammatory disorders of the gastrointestinal (GI) tract is to describe the clinical and histological features of individual disease entities. Unfortunately, rendering a specific diagnosis is not always possible when evaluating mucosal biopsies of the GI tract. Therefore it is incumbent on the pathologist to evaluate all of the clinical, endoscopic, and histological features in each case to help establish…

Drug-Induced Disorders of the Gastrointestinal Tract

Introduction Given the plethora of drugs available by prescription and over the counter, and that most are administered orally, it is not surprising that many drugs can cause gastrointestinal (GI) disease. The injury caused by drugs can be due to direct toxic effects of the drug on the GI mucosa, toxic effects to the mesenchymal components of the gut, including the enteric nervous system, systemic effects…

Vascular Disorders of the Gastrointestinal Tract

Introduction The gastrointestinal (GI) tract performs energy-demanding functions of digestion and absorption of nutrients while maintaining a critical barrier between the internal milieu and the external (luminal) environment. It also contributes to the activities of the immune system. These functions depend on a reliable blood supply. It is not surprising, therefore, that vascular disorders have important clinical manifestations. Vascular disorders usually manifest clinically as bleeding or…

Enteropathies Associated with Chronic Diarrhea and Malabsorption in Childhood

Introduction and General Remarks The aims of this chapter are to review the pathological features of the major intestinal disorders of infancy and early childhood, with an emphasis on congenital disorders resulting in chronic diarrhea and malabsorption, and to illustrate their appearance on small-intestinal biopsies and specimens ( Box 10.1 ). Other major categories of disorders that can cause chronic diarrhea, such as infections, immunodeficiencies (primary…

Congenital and Developmental Disorders of the Gastrointestinal Tract

Molecular Mechanisms of Gastrointestinal Development Recent advances in our understanding of the molecular controls of gut development have flowed from studies of a number of vertebrate and invertebrate models, including Caenorhabditis elegans (roundworm), sea urchins, Drosophila, zebrafish, and the mouse. These have provided insight into the genetic mechanisms that direct formation and modeling of the gastrointestinal (GI) tract, highlighted the importance of endodermal-mesenchymal interactions, and demonstrated…

Neuromuscular Disorders of the Gastrointestinal Tract

Introduction Normal bowel motility depends on smooth muscle, interstitial cells of Cajal (ICC), the intrinsic and extrinsic nerve supply and their supporting cells, and various neuroendocrine peptides. Abnormalities in any one or more of these components may result in bowel dysmotility. In addition, other inflammatory cells such as lymphocytes, eosinophils, and mast cells may act directly, or indirectly, on the neuromuscular apparatus of the bowel wall.…

Systemic Illnesses Involving the Gastrointestinal Tract

Introduction Systemic illnesses commonly affect the gastrointestinal (GI) tract. GI symptoms and morphological changes can result from several different pathogenetic mechanisms, such as nonspecific or constitutional symptoms, pathological changes common to intestinal and extraintestinal organs, secondary changes such as opportunistic infections or drug reactions, and metastatic disease. This chapter focuses on morphological alterations in the GI tract resulting from disorders that primarily affect other organ systems.…

Autoimmune Disorders of the Gastrointestinal Tract

Introduction The gastrointestinal (GI) tract is a rich lymphoid organ by virtue of the fact that there are numerous immune cells in the lamina propria as well as abundant lymphoid follicles and Peyer’s patches distributed throughout, which is collectively referred to as mucosa-associated lymphoid tissue (MALT). Complex interactions between enterocytes, antigen-presenting cells, lymphocytes, and other elements of the immune system occur in this specialized microenvironment. The…

Manifestations of Immunodeficiency in the Gastrointestinal Tract

Primary Immunodeficiencies Many of the primary immunodeficiencies ( Table 5.1 ) are associated with gastrointestinal (GI) lesions. Manifestations of immune deficiency in the GI tract may be broadly divided into three categories : increased susceptibility to infection, idiopathic chronic inflammatory conditions, and increased risk of neoplasia. Although many GI lesions are infectious ( Table 5.2 ), chronic inflammatory conditions resembling celiac disease and inflammatory bowel disease…

Infectious Disorders of the Gastrointestinal Tract

Acknowledgment The author wishes to thank Dr. Laura W. Lamps for her work on prior editions of the chapter. Introduction Gastrointestinal (GI) infections are a major cause of morbidity and mortality worldwide. As the number of transplant patients and those with other immunocompromising conditions increases, and as global urbanization and transcontinental travel become more frequent, the surgical pathologist must be familiar with infectious diseases that were…

Diagnostic Cytology of the Gastrointestinal Tract

Introduction The popularity of gastrointestinal (GI) cytology for the diagnosis of infection and malignancy has waxed and waned during the past few decades. The ability to distinguish between high-grade dysplasia or carcinoma in situ and invasive carcinoma in biopsy specimens and the more prevalent expertise of surgical pathology cause some to consider cytology an unnecessary duplication of GI mucosal biopsies. However, the combined use of endoscopy,…