Pathology of the Alimentary Tract 1 (Oral Cavity & Oesophagus)

Mind Map by , created almost 6 years ago

Doctorate Pathology (Systems Pathology) Mind Map on Pathology of the Alimentary Tract 1 (Oral Cavity & Oesophagus), created by melian.yates on 12/03/2013.

Created by melian.yates almost 6 years ago
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Pathology of the Alimentary Tract 1 (Oral Cavity & Oesophagus)
1 Alimentary Tract
1.1 Normal Histology (Alimentary Tract)
1.1.1 Stratified Squamous epithelium Mouth Oesophagus Non-glandular part of stomach: Pigs, Horses Forestomachs: Ruminants Anus: Keratinized: Ruminants, Horses, Pigs Non- Keratinized: Dogs & Cats
1.1.2 Simple columnar glandular epithelium Stomach; Abomasum Surface epithelium Simple tubular glands Chief (peptic, zymogen) cells: Pepsinogen Parietal (oxyntic) cells: HCl Neuroendocrine cells Stem cells: Neck of gland Small intestine Progenitor cells: Crypts Enterocytes: Villi Mucous (goblet) cells Neuroendocrine cells Large Intestine Enterocytes: Crypts, surface epithelium Mucous(goblet) cells
1.2 Defense Mechanisms (Alimentary Tract)
1.2.1 GI tract sterile at birth -> becomes colonized w/ bacteria
1.2.2 Routes of Entry: Oral ingestion Secretions swallowed from the respiratory tract Haematogenous dissemination Parasite migration
1.2.3 Secretions Saliva Mucous Inhibits contact w/ mucosa, protects surface Acid Parietal cells in stomach Digestive enzymes Salivary amylase, Pepsin from gastric chief cells, pancreatic & SI enzymes Bile secretions Kill some pathogens Flushing effect & antibacterial components (Ex. lysozyme, secretory IgA)
1.2.4 Epithelium Mucosal barrier Stomach, Intestine Tight junctions (b/w epithelial cells) Prevent entry of macromolecules & pathogens (but allows ions & H2O to diffuse through) Very high cell turnover Stratified Squamous epithelium Oral cavity Multilayered Relatively high cell turnover Keratinized surface layer at some sites
1.2.5 Commensal Flora Act as barrier to pathogens Secrete VFAs & compete w/ pathogens for nutrients Essential for digestion in herbivores Any disequilibrium of microflora can lead to disease
1.2.6 Movement Continuous movement/peristalsis discourages persistence of insult/agent
1.2.7 Cell-mediated & Humoral Defenses Lamina propria: Macrophages, B & T Lymphocytes, Plasma cells, mast cells Epithelium: Intraepithelial lymphocytes (T lymphocytes) Lymphoid Aggregates: Peyer's Patches (esp. ileum), GALT Ab production (esp. secretory IgA) Regional Lymph Nodes Omental macrophages
1.3 Inflammation in the Alimentary Tract
1.3.1 Vascular changes Hyperaemia (Congestion) Reddening, Oedema Haemorrhage: Petechiae, Ecchymoses
1.3.2 Exudates Serous/Mucous/Seromucous: Catarrhal Suppurative (Purulent) Mucopurulent Diptheritic: Fibrin & Necrotic material, secondary bactrerial invasion
2 Oral Cavity
2.1 Defense Mechanisms (Oral Cavity):
2.1.1 Taste buds Normal bacterial flora Saliva (flushing, coating, lysozyme & Igs)
2.2 Developmental Anomalies (Oral Cavity)
2.2.1 Brachygnathia superior/inferior Short maxilla/mandible
2.2.2 Prognathia Abnormal prolongation of maxilla/mandible
2.2.3 Cleft palate/palatoschisis Inadequate growth of palatine shelves leaves a central defect Communication of nasal & oral cavities may result in aspiration pneumonia & problems w/ suckling Affects hard &/or soft palate
2.2.4 Hare lip/cheiloschisis Absence of part of lip rostral to nasal septum
2.3 Inflammatory Lesions (Oral Cavity)
2.3.1 Inflammation predominates in Chronic lesions of bacterial or fungal origin
2.3.2 Granulomatous inflammation Actinobacillosis ("Wooden togue") Actinobacillus lignieresii Actinomycosis ("Lumpy jaw") Actinomyces bovis Mandible becomes enlarged due to chronic osteomyelitis
2.3.3 Eosinophilic Inflammation Oral eosinophilic granuloma (Cats)
2.3.4 Necrotizing Inflammation Calf diptheria Fusobacterium necrophorum Coagulative necrosis & surrounding granulation tissue affecting the gingival & oral mucosa
2.3.5 Vesicular Inflammation Often viral Vesicular, ulcerative or proliferative patterns may also co-exist or progress (e.g. vesicles -> ulcers) Foot & mouth disease Feline calcivirus
2.3.6 Erosive Inflammation Ulcers may progress from vesicles, but can also be caused by: some bacterial & immune-mediated diseases, trauma Feline calcivirus & Feline herpesvirus Causes mouth ulceration Mucosal Disease Bovine viral diarrhoea virus (BVDV) Causes ulceration of oral cavity, muzzle & more distal alimentary ytact Immune - mediated diseases Autoantibodies directed against epithelial cell surface Ags Ex. Pemphigus vulgaris, bullous pemphigold (Dogs, Cats & Horses)
2.3.7 Papular Inflammation Proliferative (papular) lesions Contagious pustular dermatitis ("orf") Firm, raised papules & pustules on lips & oral mucosa Sheep & Goats Hydrophobic degeneration, mixed inflammatory cell infiltration & secondary bacterial invasion
2.4 Neoplasia (Oral Cavity)
2.4.1 Epithelial Tumors Papillomas Benign Raised, sometimes cauliflower-like lesions (Lips & Oral Mucosa) Thick squamous epithelium over a branching pedunculated fibrous stroma Squamous cell carcinoma Malignant Most common oral malignancy (Cats) Ventrolateral tongue Locally invasive +/- metastases Composed of elevated firm, white plaques or nodules that may ulcerate Irregular masses & cords of squamous epithelium invading the lamina propria May be circular pearls of keratin
2.4.2 Melanoma Tumor of pigment producing melanocytes Most common oral neoplasm (Dog) Nearly always Malignant (in oral cavity) Grow rapidly & are not always pigmented Oval or spindle-shaped melanocytes w/ variable melanin content
2.4.3 Epulis Group of benign neoplasms of peridontal origin affecting gingivae Particularly in brachycephalic Dog breeds (boxer) Firm lesions on gums, surrounding teeth, esp. carnassial/canine region Dense collagenous & sometimes ossified tissue covered with stratified squamous epithelium (descends into dermis in cords)
3 Oesophagus
3.1 Congenital Anomalies
3.1.1 Segmental aplasia Rare failure of fusion Band of fibrous tissue where distal oesophagus should be
3.1.2 Achalasia Failure of cardiac sphincter to open
3.2 Functional (Neuromuscular) Disorders
3.2.1 Megaesophagus Dilated oesophagus lacks peristalsis Accumulates ingesta due to underlying neuromuscular disorder (or obstruction), but lower oesophageal sphincter is usually normal Aspiration pneumonia may be a sequel Idiopathic Developmental disorder of vagus nerve/motor nucleus (esp. Great Dane, German shepherd, Siamese cat) Acquired Neurological Dysautonomias (ex. Equine grass sickness, feline dysautonomia), Myaesthenia gravis Muscular Myodegeneration (ex. nutritional myopathy (Vit. E/ selenium deficiency in cattle)
3.3 Obstruction
3.3.1 Intraluminal Foreign bodies ("Choke") Ex. Root vegetable, sugar beet pulp, bone Most likely sites are narrow areas: Thoracic inlet, base of heart & cardiac sphincter May cause inflammation, pressure necrosis, ulceration & perforation Obstruction of Ruminant oesophagus may cause bloat Healing may cause narrowing (Stricture)
3.3.2 Intramural (w/in wall of oesophagus) Inflammatory lesion (abscess, granulation tissue), fibrosis or neoplasm => Narrowing
3.3.3 Extrinsic ( outside the oesophagus) Vascular ring anomaly (persistent RT. aortic arch constricts oesophagus & leads to megaoesophagus cranially) Also pressure from abscess, haematoma, neoplasm
3.4 Inflammation (Oesophagitis)
3.4.1 Reflux Oesophagitis Damage from gastric acid due to gastric-oesophageal reflux or vomiting => Erosion of epithelium (may progress to ulcers)
3.4.2 Infectious Agents Ex. Actinobacillosis, feline calcivirus
3.5 Neoplasia
3.5.1 Papillomatosis Cattle: Bovine papillomavirus type 4 (transforms squamous cell carcinoma w/ bracken fern toxins)
3.5.2 Squamous cell carcinoma Cats
3.5.3 Leiomyoma Benign tumor of smooth muscle