Respiratory Pathology

Question 1

Describe the pathology of asthma?

Answer 1

Type I hypersensitivity reaction (allergens/ cold/ exercise).
-Degranulation of IgE bearing mast cells: histamine initiated bronchoconstriction & mucus production, obstructing air flow. Also eosinophil chemotaxis.

Question 2

What are the persistent/ irreversible changes of asthma?

Answer 2

• Bronchiolar smooth wall hypertrophy
• Mucus gland hyperplasia
• Respiratory bronchiolitis leading to centrilobar emphysema

Question 3

What is bronchiectasis?

Answer 3

Permanent dilation of bronchi & bronchioles caused by destruction of the muscle and elastic tissue.
Results from chronic necrotizing infection (like from CF, primary ciliary dyskinesia, bronchial obstruction)

Question 4

What is COPD?

Answer 4

A combination of emphysema & chronic bronchitis (basically chronic inflammation and infections).

Question 5

What are the 3 classifications of emphysema?

Answer 5

1) Centrilobar (centiacinar) - coal dust, smoking
2) Panlobar (panacinar) - >80% are antitrypsin deficient, severest in lower lobe bases.
3) Paraseptal (distal acinar) - upper lobe subpleural bullae adjacent to fibrosis.

Question 6

How can you tell if the COPD is predominantly bronchitis or emphysema?

Answer 6

Bronchitis: 40-45, cough with copious sputum, common infections, prominant vessels & larger heart on xray, blue bloater.
Emphysema: 50-75, late cough, infections rare, small heart & hyperinflated lungs on xray, pink puffer.

Question 7

Characteristics of interstitial lung disease?

Answer 7

Restrictive lung disease.
Increased tissue in alveolar-capillary wall.
Inflammation and fibrosis
Decreased lung compliance
Increased gas diffusion distance

Question 8

What is acute interstitial lung disease?

Answer 8

Diffuse alveolar damage- exudate & death of type I pneumocytes –> form hyaline membranes lining alveoli, followed by type II pneumocytes.

Question 9

What is chronic interstitial lung disease?

Answer 9

Dyspnoea increasing for months to years.
Interstitial fibrosis & chronic inflammation with varying radiological & histological patterns.
Common end-stage fibrosed ‘honey-comb lung’

Question 10

Describe the histological appearance of Idiopathic Pulmonary Fibrosis?

Answer 10

(sub-pleural, lower lobes affected most)

• Interstitial chronic inflammation & variably mature fibrous tissue
• Similar pattern in asbestos
• Bosselated ‘cobblestone’ pleural surface

Question 11

What is sarcoidosis?

Answer 11

(typically young adult females)

• Non-caseating perilymphatic pulmonary granulomas, then fibrosis. Hilar nodes involved.
• Hypercalcaemia & elevated serum ACE

Question 12

What are the types of coal worker’s pneumoconiosis?

Answer 12

1) Anthracosis (asymptomatic, milder type- caused by accumulation of carbon)
2) Simple (macular) CWP (nodular aggregations in lungs)
3) Progressive massive fibrosis (if prolonged exposure. Large masses of dense fibrosis in the lungs).

Question 13

What is silicosis, and what might it lead to?

Answer 13

(silica= sand and stone dust). Kills phagocytosing macrophages. Fibrosis & fibrous silicotic nodules.

• Possible reactivation of TB
• Increased risk of lung carcinoma (prescribed occupational disease in UK)

Question 14

What is Hypersensitivity Pneumonitis? (aka extrinsic allergic alveolitis)

Answer 14

Type III hypersensitivity reaction, repeated episodes lead to interstitial fibrosis.

• FARMER’S LUNG= actinomycetes in hay
• PIGEON FANCIER’S LUNG= pigeon antigens

Question 15

What aspects of the GI system are affected by Cystic Fibrosis?

Answer 15

Small Bowel: mucus plugging- meconium ileus
Liver: plugging of bile cannaliculi- cirrhosis
Salivary glands & pancreas: atrophy & fibrosis

Question 16

What are the 4 major types of primary malignant lung tumours (mostly carcinomas)?

Answer 16

1. Squamous cell carcinoma (20-30%)
2. Small cell carcinoma (15-20%)
3. Adenocarcinoma (30-40%)
4. Large cell undifferentiated carcinoma (10-15%)

Question 17

Aetiology of Lung tumours?

Answer 17

Tobacco smoking
Occupational/ Industrial hazards (eg asbestos, arsenic)
Radiation (mines- radon)
Lung fibrosis
Genetic Mutations (EGFR, KRAS, ALK)

Question 18

What are the electrolytic disturbances of small cell carcinoma?

Answer 18

Hyponatraemia
Hypokalaemia
Hypercalcaemia

Question 19

What happens in a normal pleural mesothelium?

Answer 19

Single layer of mesothelial cells lines the pleural cavity

Secrete hyaluronic acid rich mucinous pleural fluid (lubricates movement of visceral & parietal pleura)

Question 20

What are the 2 types of asbestos associated pleural fibrosis?

Answer 20

• Parietal pleural fibrous plaques

- Diffuse pleural fibrous

Question 21

Characteristics of Parietal pleural fibrous plaques?

Answer 21

• Associated with low level asbestos dust exposure
• Asymptomatic, may be visible of chest radiographs
• Dense poorly cellular collagen
• Not eligible for Industrial Injuries Disablement Benefit

Question 22

Characteristics of Diffuse pleural fibrosis?

Answer 22

• Associated with high level asbestos dust exposure
• Usually bilateral, prevents normal expansion of lung causing breathlessness.
• Dense cellular collagen (not extending into interlobar fissures)
• Eligible for Industral Injuries Disablement Benefit

Question 23

What are features of Transudate Pleural Effusion?

Answer 23

1- Low capillary oncotic pressure (due to hypoalbumenaemia) & high capillary hydrostatic pressure
2- Low protein and low lactate dehydrogenase
3- Intact capillaries retain semipermeability

Question 24

What is an Exudate Pleural Effusion caused by?

Answer 24

Inflammation (with or without infection)

Neoplasms either primary or secondary

Question 25

What are features of Exudate Pleural Effusion?

Answer 25

1- Normal capillary oncotic pressure & normal vascular hydrostatic pressure 2- High protein & high lactate dehydrogenase 3- Capillaries lose semipermeability

Question 26

What is an open pneumothorax?

Answer 26

Chest wall perforation (usually traumatic- 'sucking chest wound') External air is drawn into the pleural cavity during inspiration, reducing potential lung expansion.

Question 27

What is a closed pneumothorax?

Answer 27

``` Lung perforation (usually not traumatic), connects the lung air spaces to the pleural cavity. Lung air is drawn into the pleural cavity during inspiration, reducing potential lung expansion. ```

Question 28

What is a tension pneumothorax?

Answer 28

The perforation into the pleural cavity can be valvular (allowing air into cavity during inspiration, but not out during expiration) Pressure in pneumothorax can rise above atmospheric pressure. Can compress mediastinal structures

Question 29

What is a malignant mesothelioma?

Answer 29

A neoplasm of the mesothelial cells that line serious cavities (pleura, peritoneum, peridcardium) 92% are pleural (and more common in men), 8% are peritoneal.

Question 30

Causes of malignant mesothelioma?

Answer 30

- Asbestos (80-90% of cases) - Thoracic irradiation - BAP1 (BRCA1-associated protein)

Question 31

What are 3 types of asbestos? (fibrous metal silicates)

Answer 31

- Amphibole: blue aspestos (crocidolite) - Brown aspestos (amosite) - Serpentine: white aspestos (chrysotile)

Question 32

What is the oncogenicity of amphiboles and chrysotile?

Answer 32

Amphiboles: most oncogenic and persists in the lungs. Chrysotile: less oncogenic and is more readily cleared from the lungs.

Question 33

What is asbestosis?

Answer 33

Interstitial pneumonia-like progressive pulmonary fibrosis caused by exposure to aspestos dust. Fibrosis of the alveolar walls impairs both gas exchange and lung expansion.

Question 34

What are asbestos corns?

Answer 34

Benign hyperkeratotic wart-like skin lesions

Question 35

What is the Centor criteria?

Answer 35

(indication of the likelihood of a sore throat being due to bacterial infection) - Tonsillar exudate - Tendor anterior cervical lymphadenopathy - Fever over 38C - Absence of cough

Question 36

What are the triad of symptoms in Infectious mononucleosis/ glandular fever/ kissing disease (EPV)?

Answer 36

Fever, tonsillar pharyngitis and cervical lymphadenopathy. | avoid ampicillin due to mac-pap rash

Question 37

What is the commonest cause of epiglottitis?

Answer 37

Haemophillusinfluenzae type b (Hib) - in 90% paediatric cases.

Question 38

What are the 2 causes of acute otitis externa? (Acute OE)

Answer 38

- 90% bacterial (Pseudonomas aeruginosa & Staphylococcus aureus) - 10% fungal

Question 39

What is malignant (necrotising) Otitis Externa?

Answer 39

Occurs when external otitis spreads to the skull base (soft tissue, cartilage and bone of the temporal region & skull) Commonly develops in elderly diabetic or immunocompromised patients. Severe pain, otorrhoea, granulation tissue in canal floor, cranial nerve palsy.

Question 40

What is chronic Otitis Externa?

Answer 40

Pruritus, mild discomfort, erythematous external canal devoid of wax White keratin debris may fill ear canal Common cause is allergic contact dermatitis

Question 41

What organisms cause Otitis Media?

Answer 41

Viruses! = Streptococcus pneumoniae, Haemophilusinfluenzae and Moraxella catarrhalis

Question 42

What is mastoiditis?

Answer 42

Complication of Otitis Media. Infection of the mastoid bone and air cells. Rare in adults. CT scan always required.

Question 43

What are the 2 anatomical patterns of pneumonia?

Answer 43

1) Bronchopneumonia- characteristic patchy distribution centred on inflamed bronchioles/bronchi, then subsequent spread to surrounding alveoli. 2) Lobar pneumonia- affects a large part, or the entire lobe (90% due to S. pneumoniae)

Question 44

What are some causative organisms in Community-Acquire Pneumonia?

Answer 44

Bacterial causes often divided into 'typical' and 'atypical'... Typical (have cell wall): Strep. pneumoniae, Haemophillus influenzae, Staph. aureus Atypical (no cell wall): Mycoplasma pneumoniae, Legionella pneumophilia

Question 45

What is used as an assessment of disease severity in CAP?

Answer 45

CURB-65 score | sputum culture, blood culture, pneumococcal/ legionella urinary antigen

Question 46

What are 3 complications of pneumonia?

Answer 46

1) 3-5% pleural effusion 2) 1% Empyema (pus in pleural space) 3) Lung abscess (suppuration & destruction of lung parenchyma)

Question 47

Viral LRTI, what are the causative agents for pneumonia in the normal host?

Answer 47

Adults: Influenza A & B, Adenovirus, Varicella zoster virus (VZV) Children: RSV, Parainfluenza

Question 48

What is Rhinovirus?

Answer 48

Agent responsible for most 'common colds', can cause LRTI and trigger exacerbations of asthma.

Question 49

What is a method of prevention of LRTIs?

Answer 49

``` Pneumococcal vaccination (S. pneumoniae) -for patients with chronic heart/ lung/ kidney disease and splenectomy. ```

Question 50

What is PCP (Pneumocystis jiroveci Pneumonia)?

Answer 50

A fungus, but lacks ergosterol in its cell wall & is not susceptible to a number of antifungals.

Question 51

What sort of % of tobacco smokers develop lung cancer, and what are some other risks associated?

Answer 51

11% - P450 polymorphisms - Industrial hazards - Air pollution

Question 52

What is the most common tumour found in lung?

Answer 52

Metastatic | if primary= squamous cell

Question 53

Why may young females (<50yrs) who have never smoked but develop lung cancer (adenocarcinoma)?

Answer 53

Associated with EGFR mutation.

Question 54

What is paraneoplastic syndrome of inappropriate antidiuretic hormone secretion (SIADH) associated with?

Answer 54

Small cell lung carcinoma (Paraneoplastic syndromes: caused by ectopic hormone production or immune-mediated tissue destruction caused by antigens expressed on cancer cells- caused by a number of malignancies but most commonly lung, breast, ovary )