Normal gastrointestinal tract and variations on endoscopy

Abbreviations

Introduction

Crohn’s disease (CD) can affect any part of the gastrointestinal (GI) tract, while classic ulcerative colitis (UC) only involves colon and rectum. Differential diagnosis between inflammatory bowel disease (IBD) and other inflammatory, neoplastic, medication-related, and organ transplantation–related disease conditions is discussed in separate chapters. On the other hand, identification of normal endoscopic features of the esophagus, stomach, small and large intestine, and anorectum is critical for the diagnosis and differential diagnosis. In addition, there are “normal variations” on endoscopy of the GI tract. Some of these variations can mimic IBD, IBD-associated complications, and other inflammatory or neoplastic conditions. The normal anatomy and their common alterations in IBD- or non-IBD conditions are demonstrated.

Esophagus

The inner layer of the esophagus is covered with whitish squamous cells, in contrast to the salmon-color columnar epithelia in the stomach. The longitudinal vascular pattern is visible, especially in the distal esophagus, close to the esophagogastric junction ( Fig. 3.1A ). Congenital cervical inlet patch is occasionally found in the proximal esophagus ( Fig. 3.1B ). The cervical inlet patch consists of the ectopic gastric mucosa. Due to acid secretion from ectopic gastric mucosa may lead to esophagitis, ulcer, web, or stricture, mimicking CD of the esophagus.

Glycogenic acanthosis is characterized by multifocal plaques of hyperplastic squamous epithelium with abundant intracellular glycogen deposits in the entire esophagus. Glycogenic acanthosis needs to be differentiated from Candida esophagitis ( Fig. 3.1C and D ).

Linear white specks are occasionally seen in the normal esophagus ( Fig. 3.2A ), which should be differentiated from white plaques in those with Candida esophagitis. Patients with esophageal spasms, a functional disorder of the esophagus, may present with linear furrows and esophageal rings ( Fig. 3.2B ), which resemble to that seen in eosinophilic esophagitis ( Fig. 3.2C and D ). The distinction may only be made by histologic evaluation.