Atlas of Gastrointestinal Pathology

CONTENTS
1 ESOPHAGUS ..................................................................................................1
The Unremarkable Esophagus .......................................................................2
Acute Esophagitis Pattern ..............................................................................7
Gastroesophageal reflux disease ........................................................................ 7
Infections ........................................................................................................... 10
Medications ....................................................................................................... 19
Other (malignancy, amyloidosis, radiation injury, and vasculitis) ....................... 30
Eosinophilic Pattern ......................................................................................32
Eosinophilic esophagitis (EoE) ........................................................................... 33
Gastroesophageal reflux disease ...................................................................... 37
Drug reaction ..................................................................................................... 38
Allergy ............................................................................................................... 38
Photodynamic therapy ...................................................................................... 39
Systemic collagen vascular disorders (scleroderma) .......................................... 40
Parakeratotic Pattern ....................................................................................40
Gastroesophageal reflux disease ...................................................................... 41
Candida ............................................................................................................. 42
Leukoplakia pattern/epidermoid metaplasia .................................................... 44
Esophagitis dissecans superficialis/sloughing esophagitis ................................ 46
Esophageal Lymphocytosis Pattern..............................................................49
Gastroesophageal reflux disease ...................................................................... 50
Crohn disease .................................................................................................... 50
Contact mucositis .............................................................................................. 52
Candida ............................................................................................................. 52
Common variable immunodeficiency ................................................................ 52
Dysmotility disorders ......................................................................................... 53
Lichen planus/“lichenoid” pattern .................................................................... 53
Graft-versus-host disease .................................................................................. 56
Pigments .......................................................................................................59
Near Misses ..................................................................................................59
Gastric inlet patch/heterotopic gastric mucosa ................................................. 59
Pancreatic heterotopia/metaplasia .................................................................... 60
Glycogenic acanthosis ....................................................................................... 62
Squamous papilloma ......................................................................................... 65
Multilayered epithelium ..................................................................................... 67
Amyloid ............................................................................................................. 68
Granular cell tumor ............................................................................................ 69
Granulomata ...................................................................................................... 71
Apoptotic body prominence ............................................................................. 72
Ring mitoses (taxol and colchicine) ................................................................... 73
Malignancy ........................................................................................................ 74
Appendix ......................................................................................................74
1% Alcian blue, pH 2.5 Recipe .......................................................................... 74
PAS/AB pH 2.5 Recipe ...................................................................................... 74
2 STOMACH ....................................................................................................81
The Unremarkable Stomach .........................................................................82
Layers ................................................................................................................ 82
Histology and function ...................................................................................... 83
Reactive Gastropathy Pattern ......................................................................87Acute Gastritis Pattern .................................................................................92
Medications ....................................................................................................... 92
Infections ........................................................................................................... 94
Focally enhanced gastritis ............................................................................... 106
Chronic Gastritis Pattern ............................................................................108
Autoimmune metaplastic atrophic gastritis ..................................................... 108
Environmental metaplastic atrophic gastritis ................................................... 112
A patterns-based approach to chronic gastritis .............................................. 112
Lymphocytic Gastritis Pattern.....................................................................122
Collagenous Gastritis Pattern.....................................................................128
Gastric Eosinophilia Pattern .......................................................................130
Idiopathic eosinophilic gastritis ....................................................................... 132
Medications ..................................................................................................... 132
Parasitic infection............................................................................................. 134
Inflammatory bowel disease ............................................................................ 134
Connective tissue disorder and vasculitis ........................................................ 135
Neoplasia ........................................................................................................ 135
Hyperplasia Pattern ....................................................................................136
Oxyntic gland hyperplasia ............................................................................... 137
Foveolar hyperplasia ....................................................................................... 143
Granulomatous Gastritis Pattern ................................................................148
Vascular and Hemorrhagic Changes Pattern ..............................................151
Portal hypertensive gastropathy ...................................................................... 152
Gastric antral vascular ectasia.......................................................................... 153
Doxycycline-induced injury.............................................................................. 155
Amyloid ........................................................................................................... 156
Radiation gastritis pattern ............................................................................... 156
Pigments and Extras ...................................................................................158
Iron .................................................................................................................. 158
Gastric pseudomelanosis ................................................................................ 161
Calcinosis ......................................................................................................... 162
Resins .............................................................................................................. 164
90
Yttrium-labeled microspheres ....................................................................... 164
Near Misses ................................................................................................166
Amyloidosis ..................................................................................................... 166
Apoptotic body prominence ........................................................................... 167
Poorly differentiated adenocarcinoma with signet ring cell features .............. 167
Russell body gastritis ....................................................................................... 169
Mucous neck cells ........................................................................................... 170
Sarcina ............................................................................................................. 170
Bezoar and other foreign material ................................................................... 171
Mast cell disease ............................................................................................. 172
3 SMALL BOWEL ...........................................................................................185
The Unremarkable Small Bowel .................................................................186
Acute Duodenitis Pattern ...........................................................................195
Peptic injury ..................................................................................................... 196
Infection ........................................................................................................... 197
Inflammatory bowel disease ............................................................................ 199
Immunoglobulin A (IgA) vasculitis ................................................................... 200
Acute Ileitis Pattern ....................................................................................201
Medications ..................................................................................................... 202
Inflammatory bowel disease ............................................................................ 203
Chronic Inflammation Pattern .................................................................... 207
Crypt Architectural Disturbance Pattern ....................................................209
Inflammatory bowel disease ............................................................................ 210
Diaphragm disease .......................................................................................... 212Graft-versus-host disease ................................................................................ 219
Medications ..................................................................................................... 222
Allograft rejection, small bowel ....................................................................... 223
Radiation enteritis ............................................................................................ 226
Pouchitis and pouch-related changes ............................................................. 227
Eosinophilia Pattern ...................................................................................234
Malabsorption Pattern ...............................................................................236
Overview of malabsorption patterns ............................................................... 236
Medications ..................................................................................................... 238
Reactive duodenopathy .................................................................................. 239
Small intestinal bacterial overgrowth .............................................................. 241
Gluten-sensitive enteropathy (celiac disease) ................................................. 244
Nongluten protein sensitivity .......................................................................... 252
Tropical sprue .................................................................................................. 253
Common variable immunodeficiency .............................................................. 255
Inflammatory bowel disease ............................................................................ 256
Autoimmune enteropathy ............................................................................... 257
Collagenous enteritis ....................................................................................... 259
Foamy Macrophage Pattern .......................................................................261
Mycobacterium avium complex ...................................................................... 262
Whipple disease .............................................................................................. 264
Nonspecific scattered macrophages ............................................................... 269
Dilated Lacteal Pattern ...............................................................................270
Primary lymphangiectasia ................................................................................ 270
Secondary lymphangiectasia ........................................................................... 271
Metaplasia and Heterotopia.......................................................................274
Reactive duodenopathy .................................................................................. 274
Gastric heterotopia .......................................................................................... 276
Pancreatic heterotopia .................................................................................... 277
Pyloric metaplasia ............................................................................................ 278
Pigments and Extras ...................................................................................280
Titanium (“peyer patch pigment”) .................................................................. 281
Tattoo pigment ................................................................................................ 282
Pseudomelanosis duodeni .............................................................................. 283
Formalin pigment (acid formaldehyde hematin) ............................................. 285
Melanoma ........................................................................................................ 286
90
Yttrium-labeled microspheres ....................................................................... 287
Near Misses ................................................................................................290
Sneaky adenocarcinoma .................................................................................. 290
Isospora ........................................................................................................... 291
Giardia duodenalis (giardia lamblia or giardia intestinalis) .............................. 294
Common variable immunodeficiency .............................................................. 295
Collagenous enteritis ....................................................................................... 296
Sneaky neuroendocrine tumor ........................................................................ 297
4 COLON .......................................................................................................309
The Unremarkable Colon ...........................................................................310
Focal Active Colitis Pattern ........................................................................314
Acute self-limited colitis .................................................................................. 316
Acute Colitis Pattern ..................................................................................316
Cytomegalovirus.............................................................................................. 317
Salmonella ....................................................................................................... 319
Shigella ............................................................................................................ 321
Campylobacter ................................................................................................ 322
Ischemic Colitis Pattern ..............................................................................323
Ischemia ........................................................................................................... 324
Infection (Escherichia coli 0157:H7 and Clostridioides difficile) ...................... 329Pseudomembranous Pattern ......................................................................332
Chronic Colitis Pattern ...............................................................................335
A three-step approach to the chronic colitis pattern....................................... 336
Inflammatory bowel disease ............................................................................ 343
Curable inflammatory bowel disease mimics .................................................. 353
Diverticular disease ......................................................................................... 354
Diversion-associated colitis ............................................................................. 358
Sexually transmitted infectious colitis .............................................................. 361
Cord colitis syndrome ...................................................................................... 365
Immune check point inhibitor colitis ............................................................... 366
Resins .............................................................................................................. 370
Lymphocytic Pattern ...................................................................................370
Lymphocytic colitis .......................................................................................... 371
Collagenous colitis .......................................................................................... 373
Medications ..................................................................................................... 376
Eosinophilia Pattern ...................................................................................376
Idiopathic eosinophilic colitis .......................................................................... 377
Inflammatory bowel disease ............................................................................ 378
Allergy ............................................................................................................. 378
Medications ..................................................................................................... 379
Infection ........................................................................................................... 380
Collagen vascular disorder and vasculitis ........................................................ 381
Granulomatous Pattern ..............................................................................383
Apoptotic colopathy pattern ........................................................................... 387
Pigments and Extras ...................................................................................389
Melanosis coli (also referred to as pseudomelanosis coli) ............................... 389
Tattoo pigment ................................................................................................ 392
Air artifact and intramucosal lipoma ................................................................ 393
Pneumatosis cystoides intestinalis ................................................................... 396
Muciphages ..................................................................................................... 398
Resins .............................................................................................................. 399
Near Misses ................................................................................................400
Endometriosis .................................................................................................. 400
Benign signet ring cell change ........................................................................ 401
Pulse granulomata ........................................................................................... 402
Lifting agents granulomata.............................................................................. 404
Spirochetosis ................................................................................................... 405
APPENDIX A .....................................................................................................415
APPENDIX B .....................................................................................................451
INDEX ...............................................................................................................471