Gastrointestinal Pathology and Liver Metastasis: A Case-Based Approach to Diagnosis

Sanjay Kakar is Professor of Pathology and Chief of Gastrointestinal and Hepatobiliary Pathology Service at the University of California, San Francisco, in San Francisco, California. Amitabh Srivastava works in the Department of Pathology at Brigham and Women's Hospital, Boston, Massachusetts.

• Part 1: Esophagus, 1Inflammatory Disorders1.1 Eosinophilic Esophagitis Versus Reflux Esophagitis1.2 Lymphocytic Esophagitis Versus Candida Esophagitis Versus Lichen Planus Esophagitis1.3 Candida Esophagitis Versus Other Neutrophil-Predominant Esophagitis1.4 Viral Esophagitis Versus Pill and Corrosive Esophagitis1.5 Epidermoid Metaplasia Versus Glycogenic Acanthosis1.6 Melanosis or Melanocytosis (“Brown” Esophagus) Versus Acute Necrosis (“Black” Esophagus)Glandular Dysplasia and Carcinoma1.7 Columnar-Lined Esophagus Versus Barrett’s Esophagus1.8 Multilayered Epithelium Versus Barrett’s Esophagus1.9 Ancillary Stains for the Diagnosis of Barrett’s Esophagus1.10 Barrett’s Esophagus Versus Carditis With Intestinal Metaplasia1.11 Reactive Changes Versus Dysplasia (Including “Crypt Dysplasia”) in Barrett’s Esophagus1.12 Low-Grade Versus High-Grade Conventional Dysplasia1.13 Conventional Versus Foveolar Dysplasia1.14 p53 Immunohistochemistry for Diagnosis of Dysplasia in Barrett’s Esophagus1.15 High-Grade Dysplasia Versus Intramucosal Adenocarcinoma1.16 Early Adenocarcinoma Reporting in Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection Specimens1.17 Esophageal Adenocarcinoma VariantsSquamous Dysplasia and Carcinoma1.18 Grading and Management of Squamous Dysplasia1.19 Typical and Variant Squamous Cell CarcinomaUncommon and Rare Esophageal Tumors and Therapy-Related Changes1.20 Giant Fibrovascular Polyp Versus Atypical Lipomatous Tumor1.21 Leiomyoma Versus Granular Cell Tumor1.22 Poorly Differentiated and Undifferentiated Esophageal Carcinomas1.23 Diagnostic Challenges in Post-neoadjuvant Esophageal Cancer Resection Specimens1.24 Esophageal Adenocarcinoma Versus Salivary Gland-Type Tumors1.25 Primary Versus Secondary Esophageal CarcinomasPart 2: StomachBenign Conditions2.1 Normal Stomach Versus Chronic Gastritis2.2 Chronic Gastritis Versus Reactive Gastropathy2.3 Helicobacter Pylori Gastritis: To Stain or Not to Stain2.4 Autoimmune Gastritis Versus Helicobacter Gastritis2.5 Iron Pill Gastropathy Versus Other Gastric Siderosis2.6 Doxycycline Injury Versus Nonspecific Erosion2.7 Lanthanum Injury Versus Other Histiocytic Infiltration2.8 Lymphocytic Versus Collagenous Gastritis2.9 Gastric Biopsy With Increase in Eosinophils2.10 Acute Gastritis With Ulcer Versus Cytomegalovirus Gastritis2.11 Acute Gastritis With Ulcer Versus Adenovirus Gastritis2.12 Phlegmonous Gastritis2.13 Chronic Gastritis With Intestinal Metaplasia: To Type or Not to Type2.14 Chronic Gastritis With Reactive Changes Versus Intestinal-Type Dysplasia2.15 Chronic Gastritis With Reactive Changes Versus Foveolar Dysplasia2.16 High-Grade Dysplasia Versus IntramucosalAdenocarcinomaPolyps2.17 Hyperplastic Polyp Versus Fundic Gland Polyp2.18 Hyperplastic Polyp With Dysplasia Versus Intestinal-Type Adenoma2.19 Pyloric Gland Adenoma Versus Foveolar-Type Adenoma2.20 Oxyntic Gland Adenoma Versus Other Adenomas2.21 Hyperplastic Polyp Versus Peutz-Jeghers Polyp2.22 Multiple Fundic Polyps Versus Gastric Adenocarcinoma and Proximal Polyposis of the StomachMalignant Epithelial Tumors2.23 Gastric Adenocarcinoma: Intestinal Versus Diffuse Type2.24 Lymphocyte-Rich/Epstein-Barr Virus-Positive Versus Mismatch Repair Deficient Adenocarcinoma2.25 Hepatoid Carcinoma Versus Poorly-Differentiated Adenocarcinoma2.26 Enteroblastic Adenocarcinoma Versus Conventional Adenocarcinoma2.27 Signet Ring Cell Carcinoma Versus Pseudo Signet Ring Cells2.28 Signet Ring Cell Carcinoma: Sporadic Versus Familial2.29 Signet Ring Cell Carcinoma: Primary Versus Metastatic2.30 Sarcomatoid Carcinoma Versus Sarcoma2.31 Gastroblastoma Versus Adenocarcinoma2.32 Gastric Adenocarcinoma With HER2 Staining2.33 Gastric Adenocarcinoma With Programmed Cell Death Ligand 1 Staining2.34 Well-Differentiated Neuroendocrine Tumor in Autoimmune Gastritis (Type 1) Versus Neuroendocrine Hyperplasia2.35 Well-Differentiated Neuroendocrine Tumor: Sporadic (Type 3) Versus Other Types (Types 1 and 2) and Neuroendocrine CarcinomaPart 3: Small IntestineBenign Conditions3.1 Gastric Heterotopia Versus Neoplasm3.2 Pediatric Small Intestinal Biopsies in Intractable Diarrhea3.3 Small Bowel Disorders: Celiac Disease and Mimics3.4 Small Bowel Infection: Protozoal, Microsporidial, Viral3.5 Macrophage Infiltrates: Infectious Versus Non-Infectious Etiologies3.6 Heterotopic Pancreas Versus Neoplasm3.7 Active Ileitis With Crystals Versus Crohn’s DiseasePolyps3.8 Adenoma With High-Grade Dysplasia Versus Invasive Adenocarcinoma3.9 Pyloric Gland Adenoma Versus Brunner Gland HamartomaTumors3.10 Dystrophic Fat Versus Adenocarcinoma3.11 Well-Differentiated Neuroendocrine Tumor Versus Neuroendocrine Carcinoma3.12 Multilocular Peritoneal Inclusion Cyst Versus Malignant Mesothelioma3.13 Gangliocytic Paraganglioma Versus Well-Differentiated Neuroendocrine Tumor of the Small Intestine3.14 Ampullary Adenocarcinoma (pT2 Vs pT3)3.15 Small Intestinal Adenocarcinoma Versus Metastatic AdenocarcinomaPart 4: AppendixBenign Conditions4.1 Acute Appendicitis With Diverticulitis Versus Low-Grade Appendiceal Mucinous Neoplasm4.2 Sessile Serrated Adenoma Versus Mucosal Hyperplasia4.3 Benign Subserosal Glands (Endosalpingiosis) Versus AdenocarcinomaMalignant Tumors4.4 Low-Grade Appendiceal Mucinous Neoplasm Versus Appendiceal Adenoma4.5 Low-Grade Appendiceal Mucinous Neoplasm Versus Distended Appendix With Mucin4.6 Low-Grade Appendiceal Mucinous Neoplasm With Serosal Acellular Mucin and Other Risk Factors in Low-Grade Appendiceal Mucinous Neoplasm4.7 Low-Grade Appendiceal Mucinous Neoplasm Versus High-Grade Appendiceal Mucinous Neoplasm4.8 Mucinous Carcinoma Peritonei (Pseudomyxoma Peritonei), Low Grade (Grade 1) Versus High Grade (Grade 2)4.9 Mucinous Carcinoma Peritonei (Pseudomyxoma Peritonei), Grade 2 Versus Grade 34.10 Goblet Cell Adenocarcinoma Versus Neuroendocrine Neoplasms and Conventional Adenocarcinoma4.11 Appendiceal Neuroendocrine Tumor: Low- Versus High-Risk Features4.12 Tubular Neuroendocrine Tumor Versus AdenocarcinomaPart 5: ColonInflammatory Disorders5.1 Infectious Colitis Versus Inflammatory Bowel Disease5.2 Ischemic Versus Pseudomembranous Colitis5.3 Graft-Versus-Host Disease Versus Bowel Prep Effect5.4 Eosinophilic Colitis Versus Infiltrative Disorders With Prominent Eosinophils5.5 Enterocolic Lymphocytic Phlebitis Versus Inflammatory Bowel Disease5.6 Lymphocytic Versus Collagenous Colitis5.7 Diverticular Disease-Associated Colitis Versus Inflammatory Bowel Disease5.8 Diversion Colitis Versus Inflammatory Bowel Disease5.9 Isolated Asymptomatic Chronic Colitis and Ileitis Versus Inflammatory Bowel Disease5.10 Drug-Induced Colitis Versus Inflammatory Bowel Disease5.11 Radiation Colitis Versus Inflammatory Bowel Disease5.12 Solitary Rectal Ulcer Syndrome Versus Inflammatory Bowel Disease5.13 Ulcerative Colitis Versus Crohn’s Disease5.14 Fulminant Colitis Versus Infectious Colitis5.15 Crohn’s Disease Versus Sarcoidosis5.16 Pouchitis Versus Crohn’s Disease5.17 Isolated and Multiple Ulcers: Crohn’s Versus Drug Versus Other Etiologies5.18 Reactive Epithelial Changes Versus Dysplasia in Inflammatory Bowel Disease5.19 Conventional Low- Versus High-Grade Dysplasia in Inflammatory Bowel Disease5.20 Conventional Dysplasia Versus Dysplasia Variants in Inflammatory Bowel Disease5.21 Microscopic Colitis and Inflammatory Bowel Disease Overlap5.22 Kayexelate Versus Other Crystals5.23 Chronic Intestinal Pseudo-obstruction Versus Hirschsprung DiseaseColon Polyps and Polyposis Syndromes5.24 Serrated Polyps Versus Adenomas5.25 Tubular Adenoma With Squamoid Morules Versus Composite Adenoma-Microcarcinoid5.26 Tubular Adenoma Versus Endometriosis and Mucosal Colonization by Cancer5.27 Adenoma With Misplaced Epithelium (“Pseudoinvasion”) Versus Adenocarcinoma5.28 Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection Reporting of Adenocarcinoma in Polyp5.29 Familial Adenomatous Polyposis Versus Other Adenomatous Polyposis Syndromes5.30 Serrated Polyposis Syndrome Versus Multiple Hyperplastic Polyps5.31 Mucosal Prolapse Versus Peutz-Jeghers Polyp5.32 Juvenile Polyps Versus Inflammatory Polyp5.33 Cowden Syndrome Versus Cronkhite-Canada Syndrome5.34 Tailgut Cyst Versus Other Retrorectal CystsColon Carcinomas: Diagnosis and Staging5.35 Adenocarcinoma Not Otherwise Specified Versus Special Types5.36 Well- Versus Moderately Versus Poorly Differentiated Adenocarcinoma5.37 pT3 Versus pT4a Colorectal Cancer5.38 Lymphovascular Invasion in Colorectal Carcinoma5.39 Tumor Deposits Versus Nodal Metastasis Versus Venous Invasion5.40 Poorly Differentiated Neuroendocrine Carcinomas Versus Well-Differentiated Neuroendocrine Tumors Versus Mixed Neuroendocrine-Nonneuroendocrine Neoplasm5.41 Primary Versus Metastatic Carcinoma5.42 Isolated Tumor Cells Versus Micrometastasis Versus Positive Lymph Nodes5.43 Positive Versus Negative Radial MarginsPart 6: Anal CanalInfections and Preneoplastic Conditions6.1 Treponema pallidum Versus Other Infections6.2 Condyloma Versus Reactive Changes6.3 Low-Grade Versus High-Grade Squamous Intraepithelial Lesion6.4 High-Grade Squamous Intraepithelial Lesion Versus Superficially Invasive Squamous Cell Carcinoma6.5 Squamous Cell Carcinoma Versus Basal Cell Carcinoma6.6 Squamous Cell Carcinoma Versus Neuroendocrine Carcinoma6.7 Anal Gland Adenocarcinoma Versus Rectal Adenocarcinoma6.8 Paget Disease Versus High-Grade Squamous Intraepithelial Lesion6.9 Anal MelanomaPart 7: Hematopoietic Neoplasms and Mimics7.1 Gastric Extranodal Marginal Zone Lymphoma Versus Helicobacter pylori Gastritis With Lymphoid Hyperplasia7.2 Colonic Polypoid Extranodal Marginal Zone Lymphoma Versus Reactive Lymphoid Hyperplasia7.3 Mantle Cell Lymphoma7.4 Duodenal Follicular Lymphoma Versus Reactive Follicles7.5 Colonic Polypoid Follicular Lymphoma Versus Reactive Lymphoid Infiltrates7.6 Diffuse Large B-Cell Lymphoma Versus Other Large B-Cell Lymphomas7.7 High-Grade B-Cell Lymphoma Versus Other High-Grade Neoplasms7.8 Enteropathy-Associated T-Cell Lymphoma Versus Other Lymphoma7.9 Monomorphic Epitheliotropic Intestinal T-Cell Lymphoma Versus Other Lymphoma7.10 Indolent Clonal T-Cell Lymphoproliferative Disorder of the Gastrointestinal Tract Versus Lymphoma7.11 Systemic T-Cell Lymphoma Involvement of the Gastrointestinal Tract Versus Primary Gastrointestinal Lymphoma7.12 Reactive Marginal Zone Hyperplasia Versus Extranodal Marginal Zone Lymphoma7.13 Natural Killer Cell Enteropathy Versus Extranodal Natural Killer/T-Cell Lymphoma7.14 Myeloid Sarcoma Versus Other Hematopoietic or Small Round Blue Cell Tumors7.15 Systemic Mastocytosis Versus Benign Mast Cells7.16 Classic Hodgkin Lymphoma Versus Mimics7.17 Langerhans Cell Histiocytosis Versus Langerhans Cell Sarcoma7.18 Burkitt Lymphoma Versus Other Lymphoma7.19 Plasmablastic Lymphoma Versus Other Lymphoma7.20 Posttransplant Lymphoproliferative Disorder Versus Reactive Lymphoid Lesions7.21 Rectal Tonsil or Reactive Lymphoid Aggregate Versus Rectal LymphomaPart 8: Mesenchymal Tumors8.1 Gastrointestinal Stromal Tumor Versus Smooth Muscle or Neurogenic Tumor8.2 Inflammatory Myofibroblastic Tumor Versus Other Spindle Cell Neoplasms8.3 Intraabdominal Desmoid (Mesenteric Fibramatosis) Versus Gastrointestinal Stromal Tumor8.4 Solitary Fibrous Tumor Versus Other Spindle Cell Neoplasms8.5 Lipoma Versus Liposarcoma8.6 Inflammatory Fibroid Polyp (Gastric or Small Intestine) Versus Other Spindle Cell Polyps8.7 Plexiform Fibromyxoma (Gastric or Duodenum) Versus Other Spindle Cell Lesions8.8 Leiomyoma and Atypical Smooth Muscle Tumor8.9 Leiomyosarcoma Versus Other Spindle Cell Neoplasms8.10 Hemangioma or Arteriovenous Malformation Versus Other Vascular Lesions8.11 Kaposi Sarcoma (Any Gastrointestinal Site) Versus Other Spindle Cell Lesions8.12 Angiosarcoma (Any Gastrointestinal Site) Versus Other Sarcomas8.13 Glomus Tumor (Stomach) Versus Other Neoplasms8.14 Vascular Malformations (Lymphatic, Venous, Arteriovenous) Versus Hemangioma8.15 Schwannoma (Stomach) Versus Other Spindle Cell Lesions8.16 Granular Cell Tumor Versus Atypical Granular Cell Tumor (Esophagus or Large Bowel)8.17 Perineurioma or Benign Fibroblastic Polyp (Large Bowel)8.18 Ganglioneuroma and Ganglioneuromatosis (Large Bowel)8.19 Perivascular Epithelioid Cell Tumor or Angiomyolipoma Versus Other Neoplasms8.20 Synovial Sarcoma (Stomach) Versus Other Sarcomas8.21 Malignant Gastrointestinal Neuroectodermal Tumor and Gastrointestinal Clear Cell Sarcoma (Small Intestine, Stomach, Large Bowel) Versus Melanoma8.22 Colonic Ulceration With Pseudomalignant Change8.23 Endometrial Lesions and Their Mimics in the Gastrointestinal TractPart 9: Systemic Disorders Involving the Gastrointestinal Tract9.1 Amyloidosis Versus Normal Biopsy9.2 Graft-Versus-Host Disease Versus Mycophenolate Injury9.3 Scleroderma Versus Other Autoimmune Disorders9.4 Human Immunodeficiency Virus Enteritis Versus Other Immune Deficiency Disorders9.5 Esophageal Stricture Versus Immunoglobulin G4 DiseasePart 10: Liver Metastasis10.1 Metastatic Adenocarcinoma Versus Intrahepatic Cholangiocarcinoma10.2 Resection of Colorectal Cancer Metastasis10.3 Metastatic Small Intestinal Well-Differentiated NET Versus HCC Versus Other Neoplasms10.4 Metastatic Neuroendocrine Carcinoma Versus Adenocarcinoma With Neuroendocrine Features10.5 Metastatic Hepatoid Carcinoma Versus Yolk Sac Tumor Versus HCC10.6 Metastatic Epithelioid GIST Versus Primary/Metastatic Carcinoma10.7 Metastatic Anorectal Melanoma Versus Primary/Metastatic Tumors