W2 Lec 1- Obstructive lung diseases

Question 1

List the 4 common obstructive lung diseases

Answer 1

1. Chronic bronchitis
2. Emphysema
3. Athma
4. Bronchioctasis

Question 2

Discuss the features of chronic bronchitis

Answer 2

• Common in smokers and inhabitants of smog-laden cities
• Diagnosis made clinically:
  persistent cough with sputum production for at least 3 months in 2 consecutive years, in the
  absence of any other identifiable cause

Pathogenesis:
- chronic irritation by inhaled substances results in bronchial and bronchiolar injury and mucus hypersecretion

At autopsy, 2 methods in which chronic bronchitis can be quantified:
- Measure increase in gland mass in major bronchus (usually the Left main bronchus) = The Reid Index
- Count no. of terminal bronchioles in a section of the lung which show the presence of goblet cells and express this as a %
- REID INDEX of >60% signals chronic bronchitis

MORPHOLOGY:

MACROSCOPIC:
hyperaemia, swelling, oedema, excess mucopurulent secretions

MICROSCOPIC:
LARGER AIRWAYS (trachea and bronchi)
- Chronic inflammation
- Hyperplasia and hypertrophy of mucous glands – protective function
- Squamous metaplasia (changed to) – protective function

SMALLER AIRWAYS (Bronchioles):
Chronic inflammation
- Mucus plugging
- Goblet cell metaplasia
- Fibrosis

Question 3

Discuss the features of asthma

Answer 3

• Chronic inflammatory disorder of the airways causing recurrent episodes of wheezing, breathlessness,
  chest tightness and cough”
• Caused by an increased irritability of bronchi by inflammation, which leads to Bronchospasm

FIVE MAJOR TYPES OF ASTHMA
1. Atopic (Type I hypersensitivity rxn)
2. Non-atopic ( viral resp infection)
3. Drug –induced (Aspirin)
4. Occupational (fumes, organic&chemical dust, gases)
5. Allergic bronchopulmonary aspergillosis (Type I+III hypersensitivity rxn)

Question 4

Discuss the features of bronchiectasis

Answer 4

• Characterized by Permanent dilatation of the bronchi following recurrent inflammation of the bronchial wall

AETIOLOGICAL FACTORS
- Congenital/ Hereditary: Cystic fibrosis, Kartegener syndrome, etc
- Post-infectious conditions: necrotising pneumonias by bacteria (TB, Staph, Pseudomonas, Haemophilus), virus (Adeno, Influenza, HIV) and fungi (Aspergillus)
- Bronchial Obstruction: tumour, foreign body, mucus
- Impairment of normal respiratory defences: autoimmune diseases (SLE, RA, IBD)

SYMPTOMS
-Loads of mucus
- foul smelling sputum,
- recurrent infections

COMPLICATIONS:
- Pneumonia
- Lung abscess
- Septicaemia
- Amyloidosis
- Cor pulmonale

MORPHOLOGY
Macroscopic:
- dilated bronchi and bronchioles
- Honey comb appearance with cavities filled with mucus

Microscopic:
- ulceration of lining epithelium
- intense mixed acute and chronic inflammation in wall
- squamous metaplasia
- fibrosis of bronchial wall in chronic case

Question 4

Discuss Atopic Asthma

Answer 4

• Most common, begins in childhood
• Triggers: environment antigens eg dust, pollen, food, etc

MORPHOLOGY
Macroscopic: hyperinflated lungs, tenacious mucus plugs (abundance of mucus

Microscopic:
In the Bronchi : (airway remodelling)
-Inflammation - Eosinophils and Mast cells
-Mucus plugging + mucous gland hypertrophy
-Smooth muscle hypertrophy
-Thickened basement membrane

• Curshmann’s spiral (whorls shed epithelium within mucus)
• Charcot-Leyden crystals (crystals with eosinophils

Question 5

Discuss the features of emphysema

Answer 5

• Abnormal permanent enlargement of airspaces distal to terminal bronchiole, accompanied by destruction of their walls and without obvious fibrosis.

Pathogenesis:
- Related to imbalance in protease-antiprotease
system resulting in tissue destruction
- Or/and inflammation and subsequent repair