<p>SECTION 1: ESOPHAGUS<br>Nonneoplastic<br>Tracheoesophageal Fistula and Esophageal Atresia<br>Esophageal Duplication Cyst<br>Inlet Patch<br>Esophageal Webs and Rings<br>Esophageal Diverticula<br>Esophageal Varices<br>Esophageal Tears and Perforations<br>Achalasia<br>Gastroesophageal Reflux Disease<br>Eosinophilic Esophagitis<br>Pill-Induced Esophagitis<br>Corrosive Damage (Lye)<br>Sloughing Esophagitis<br>Candidal Esophagitis<br>HIV-Associated Esophageal Ulcers<br>Barrett Esophagus<br><br>Neoplastic<br>Dysplasia in Barrett Esophagus<br>Adenocarcinoma, Esophagus<br>Squamous Papilloma<br>Squamous Dysplasia<br>Squamous Cell Carcinoma, Esophagus<br>Esophageal Liposarcoma/Giant Fibrovascular Polyp<br>Granular Cell Tumor<br><br>SECTION 2: STOMACH<br>Nonneoplastic<br>Pyloric Stenosis<br>Gastric Antral Vascular Ectasia<br>Dieulafoy Lesion<br>Portal Hypertensive Gastropathy<br>Acute Hemorrhagic Gastritis<br>Chemical Gastropathy<br>Gastric Mucosal Calcinosis<br>Iron Gastropathy<br>Gastric Ulcers<br>Carditis<br>Helicobacter pylori Gastritis<br>Helicobacter heilmannii Gastritis<br>Multifocal Atrophic Gastritis<br>Autoimmune Gastritis<br>Lymphocytic Gastritis<br>Eosinophilic Gastroenteritis<br>Focally Enhanced Gastritis<br>Collagenous Gastritis<br>Granulomatous Gastritis<br>Phlegmonous Gastritis<br>Herpes Zoster Infection<br>Gastric Xanthoma<br>Hyperplastic Polyps, Stomach<br>Ménétrier Disease<br>Zollinger-Ellison Syndrome<br><br>Neoplastic<br>Fundic Gland Polyp<br>Adenoma/Dysplasia, Stomach<br>Adenocarcinoma, Stomach<br>Adenocarcinoma, Special Variants<br>Molecular Classification of Gastric Cancer<br>Hereditary Diffuse Gastric Cancer<br>Well-Differentiated Neuroendocrine Tumor (Carcinoid), Stomach<br>MALT Lymphoma<br>Gastroblastoma<br>Plexiform Fibromyxoma<br><br>SECTION 3: SMALL INTESTINE<br>Nonneoplastic<br>Small Intestine Duplication Cyst<br>Meckel Diverticulum<br>Gastric Heterotopia<br>Ectopic Pancreas<br>Microvillus Inclusion Disease<br>Necrotizing Enterocolitis<br>Primary Lymphangiectasia<br>Lymphangioma<br>Peptic Duodenitis/Duodenal Ulcer<br>Celiac Disease<br>Tropical Sprue<br>Bacterial Overgrowth/Stasis<br>Olmesartan Enteropathy<br>Autoimmune Enteropathy<br>Pouchitis<br>Whipple Disease<br>Common Variable Immunodeficiency<br>Giardia<br>Cryptosporidia<br>Cystoisospora (Isospora)<br>Cyclospora<br>Microsporidia<br>Yersinia<br>Mycobacterium avium-intracellulare<br>Mycobacterium tuberculosis<br>Strongyloides<br><br>Neoplastic<br>Adenoma, Small Intestine<br>Adenocarcinoma, Small Intestine<br>Well-Differentiated Neuroendocrine Tumor (Carcinoid), Small Intestine<br>Gangliocytic Paraganglioma<br>Enteropathy-Associated T-Cell Lymphoma<br>Follicular Lymphoma, Duodenal Type<br>Gastrointestinal Tract Clear Cell Sarcoma-Like Tumor<br>Waldenström Protein<br><br>SECTION 4: APPENDIX<br>Nonneoplastic<br>Acute Appendicitis<br>Granulomatous Appendicitis<br>Enterobius vermicularis Appendicitis<br>Fibrous Obliteration<br><br>Neoplastic<br>Serrated Polyps, Appendix<br>Appendiceal Mucinous Neoplasms<br>Well-Differentiated Neuroendocrine Tumor (Carcinoid), Appendix<br>358 Goblet Cell Adenocarcinoma<br><br>SECTION 5: COLON<br>Nonneoplastic<br>Hirschsprung Disease<br>Colonic Duplications, Cysts, and Congenital Diverticula<br>Motility Disorders<br>Diverticular Disease<br>Endometriosis<br>Preparation Artifacts<br>Melanosis Coli<br>Ulcerative Colitis, Colon<br>Crohn Disease<br>Lymphocytic Colitis<br>Collagenous Colitis<br>Eosinophilic/Allergic Colitis<br>Diversion Colitis<br>Diverticular Disease-Associated Colitis<br>Solitary Rectal Ulcer Syndrome/Mucosal Prolapse<br>Pneumatosis Cystoides Intestinalis<br>Sexually Transmitted Proctitis<br>Acute Infectious Colitis<br>Focal Active Colitis<br>Campylobacter<br>Salmonella<br>Shigella<br>Clostridium difficile<br>Enterohemorrhagic Escherichia coli<br>Spirochetosis<br>Adenovirus<br>Malakoplakia<br>Histoplasma<br>Cryptococcus<br>Entamoeba histolytica<br>Schistosomiasis<br><br>Neoplastic<br>Benign Fibroblastic Polyp/Perineurioma<br>Ganglioneuroma<br>Hyperplastic Polyps, Colon<br>Sessile Serrated Lesion (Adenoma/Polyp)<br>Mixed Adenoma-Serrated Polyp<br>Adenoma, Colon<br>Adenoma With Pseudoinvasion<br>Adenoma With Invasive Carcinoma<br>Colorectal Adenocarcinoma<br>Familial Cancer Syndromes in Colorectal Carcinoma<br>Familial Adenomatous Polyposis<br>Lynch Syndrome (Hereditary Nonpolyposis Colorectal Cancer Syndrome)<br>Serrated Polyposis<br>Hereditary Mixed Polyposis Syndrome<br>Inflammatory Bowel Disease-Associated Neoplasia<br>Well-Differentiated Neuroendocrine Tumor (Carcinoid), Colon<br>Mastocytosis<br><br>SECTION 6: ANUS<br>Nonneoplastic<br>Hemorrhoids<br>Tailgut Cyst<br><br>Neoplastic<br>Anal Intraepithelial Neoplasia<br>Squamous Cell Carcinoma, Anus<br>Basal Cell Carcinoma<br>Paget Disease<br>Anal Duct Carcinoma<br>HPV-Associated Anorectal Adenocarcinomas<br><br>SECTION 7: MULTIPLE ORGANS<br>Nonneoplastic<br>Amyloidosis<br>Cytomegalovirus<br>Herpes Simplex Virus<br>Nonsteroidal Antiinflammatory Drug (NSAID) Damage<br>Ischemia<br>Vasculitis<br>Behçet Syndrome<br>Graft-vs.-Host Disease<br>Mycophenolate Injury<br>Radiation Effect<br>Immune Modulator Therapy Effect<br>Chemotherapy Effect<br>Taxane Effect<br>Colchicine Toxicity<br>Kayexalate Injury<br>Cowden/PTEN Hamartoma Tumor Syndrome<br>Hamartomatous Polyps, Cronkhite-Canada<br>Hamartomatous Polyps, Juvenile<br>Hamartomatous Polyps, Peutz-Jeghers<br><br>Neoplastic<br>Leiomyoma<br>Leiomyosarcoma<br>Gastrointestinal Stromal Tumor<br>Mesenteric Fibromatosis<br>Inflammatory Fibroid Polyp<br>Schwannoma<br>Inflammatory Myofibroblastic Tumor<br>Glomus Tumor<br>Primary Melanoma<br>Metastatic Melanoma<br>Large B-Cell Lymphomas<br>Mantle Cell Lymphoma<br>Lipomatous Tumors<br>Follicular Dendritic Cell Sarcoma<br>Synovial Sarcoma of Gastrointestinal Tract</p>