1/6 Patterns of Disease in Lung 1 and 2 Flashcards
What it the basic organization of the airways from mouth to lungs?
Trachea –> Bronchus –> Bronchioles –> Alveoli
What are the regions of the respiratory tract?
Conducting System (nose, trachea, bronchi)
Transitional system (bronchioles)
Exchange System (Alveoli)
What type of tissue is most of the respiratory system made up of?
Ciliated respiratory epithelium (cilia + goblet cells)
What are the features of the respiratory alveolus?
Delicate thin-walled
- Blood-air barrier extremely thin!
Made up of:
- Vascular endothelium
- Basal lamina
- Alveolar epithelium (type 1- wall, type 2- surfactant)
Normal bronchiole and Alveoli histology
What routes do pathogens use to enter the respiratory system?
Aerogenous (inhaled)
Hematogenous (embolic)
Direct Entry
Lymphatic Spread
What are the basic classifications of lung inflammation (pneumonia)?
What are each one’s distribution like?
Bronchopneumonia
- enzootic, suppurative, fibrinous
- contained within an area
Interstitial pneumonia
- Infection within interstitium of lung
- Diffuse pattern, whole lung infected
Granulomatour pneumonia
- Multifocal, random distribution
Embolic
- hematogenous spread –> multifocal, random
Describe the pathogenesis of bronchopneumonia
Inhaled agent
Inflammation at the bronchoalveolar junction
Acute inflammatory response
Exudation of fluid and plasma proteins into bronchioles and alveoli
Recruitment of alveolar macrophages (resident) and emigration of neutrophils (first to respond- acute inflammation)
Describe the distribution of infection in bronchopneumonia.
Cranioventral
- Inhalation + gravity
- Affects bronchi, bronchioles, alveoli
What are the causes of bronchopneumonia?
Bacteria
- Pasteruella multocida (cattle, pigs, cats)
- Mannheimia haemolytica (cattle)
- Bordatella bronchiseptica (dogs, pigs)
Mycoplasmas
Aspiration of food/gut contents
Viruses + secondary bacterial infection
What is the route of entry with bronchopneumonia?
Inhaled
What are the types of bronchopneumonia?
Enzootic
Suppurative
Fibrinous
Aspiration
What are the etiologies of enzootic pneumonia?
Mycoplasma ovipneumoniae (ovine)
Mycoplasma hyopneumoniae (porcine)
+ secondary pathogen
What are other names for enzootic pneumonia?
Cuffing pneumonia, atypical pneumonia, chronic nonprogressive pneumonia
What is the gross appearance of a lung infected with enzootic pneumonia?
Cranioventral, dark red, sharply demarcated, combo of collapse and consolidation
What is the histological appearance of enzootic pneumonia?
Peribronchial cuffing of lymphocytes and plasma cells causing alveolar collapse
(+/- suppurative inflammation within alveoli and airways)
What type of cells do you typically see with suppurative bronchopneumonia?
Suppurative = neutrophils, usually degenerate
What are the possible etiologies of suppurative bronchopneumonia?
Most often bacterial
- Pasteurella, bordetella etc.
- Associated with aspiration of ‘bland’ contents
Viral infection predispose to bacterial infection
What infection distribution is associated with suppurative bronchopneumonia?
Cranioventral
Patchy/confluent areas/whole lobes
What does the gross anatomy of a suppurative pneumonia look like?
Lesions:
- red, consolidated, bilateral
- often sharply demarcated
Describe the histology seen with suppurative pneumonia.
Neutrophils (often degenerate) filling alveoli and airways
NO lymphocytic cuffing
Acute suppurative bronchopneumonia histology slide.
What must be present in fibrinous bronchopneumonia?
Fibrin (yellow strands, acute phase protein)
Oedema
Neutrophils (degenerate)
Necrosis
What are some possible etiologies for fibrinous pneumonia?
Cattle: Mannheimia hemolytica (shipping fever)
Porcine: Actinobacillus pleuropneumonia
Aspiration of gut contents (harsh, cause necrosis)
Describe the typical distribution of fibrinous bronchopneumonia.
Cranioventral, spreads rapidly within and between lobules
Large confluent areas/whole lobes
Often affects pleura –> pleuritis
What does fibrinous pneumonia look like grossly?
Fibrinous pleural surface
Marked expansion of interlobular septae
What can occur with a case of fibrinous pneuomonia?
Clinical signs and death can occur as result of severe toxemia and sepsis
What type of infection is shipping fever and what animal does it infect?
Acute fibrinous pneumonia
Cattle
What is etiological agent that causes shipping fever?
Mannheimia haemolytica
How does the bacteria work causing shipping fever?
Produced leukotoxin
- lyses alveolar macrophages and neutrophils
- tissue necrosis
- extensive deposition of fibrin in interlobular septa and pleura
What is the typical distribution of aspiration pneumonia?
Cranioventral (but not 100%)
What are some predisposing causes of aspiration pneumonia?
Handfeeding neonates
Megaesophagus
Cleft palate
Down animal (anesthesia)
Describe the gross appearance of aspiration pneumonia.
Green/brown/black discoloration, foul smelling
What conditions can result from acute pneumonia?
Resolution
Chronic pneumonia
- abscess formation
- Pleuritis
- Bronchiectasis
- Death
What is the typical distribution of interstitial pneumonia?
Diffuse
Is there any exudate with interstitial pneumonia?
No exudate
Describe the gross appearance of interstitial pneumonia.
Large lungs that don’t deflate
Rib impressions
Rubbery texture
What are some etiological causes of interstitial pneumonia?
Viral (canine distemper, IBR, EVR)
Inhaled toxins/gas
Toxic metabolites locally generated
Acute respiratory distress syndrome
Ventilator induced injury
Describe the distribution of granulomatous pneumonia?
Multifocal, any lobe
Describe the gross appearance of granulomatous pneumonia.
Firm nodules, with white/tan/gray/ crumbly material
Describe the histological appearance of granulomatous pneumonia.
Macrophages plus multinucleated giant cells arranged in discrete granulomas or in sheets.
What is the typical route of entry for granulomatous pneumonia?
Aerogenous/hematogenous/lymphatic spread
What are the etiological agents of granulomatous?
Bacteria
- Mycoplasma bovis
Fungal pneumonias
Verminous pneumonias
What type of pneumonia is verminous pneumonia?
Interstitial (larval migration)
Bronchitis (intrabronchial adults)
Granulomatous (aberrant parasites, dead larvae or eggs)
What is the typical distribution of verminous pneumonia?
Caudal
What is the gross appearance of verminous pneumonia?
Collapse or small nodules
What is the distribution of embolic pneumonia?
Multifocal, random
What is the route of entry with embolic pneumonia?
Haematogenous
What are some of the causes of embolic pneumonia?
Vegetative valvular endocarditis
Hepatic abscesses
Septicemia
How do primary pulmonary neoplasms arise?
Often epithelial origin (adenoma or carcinoma)
Typically have on large mass +/- intrapulmonary metastases
How do secondary neoplasia (metastatic) arise in the lungs?
Neoplasm arise somewhere else and migrate to the lungs
Lungs are popular metastatic site due to massive blood flow and capillary bed.
What are a few common metastatic tumors?
Hemangiosarcoma (spleen or right atrium)
Osteosarcoma
Mammary carcinoma
