Interstitial Lung Disease

Question 1

what is interstitial lung disease

Answer 1

disease where there is diffuse parenchymal lung injury/inflammation leading to fibrosis

Question 2

common features of interstitial lung disease

Answer 2

• dry cough
• breathlessness
• restrictive PFT pattern
• reticulonodular shadowing on CXR and HRCT

Question 3

why does the restrictive pattern happen?

Answer 3

• reduced expansion of the lung parenchyma

Question 4

radiological features of interstitial lung disease

Answer 4

• bilateral basilar reticular abnormalities

- ground-glass appearance on HRCT thorax

Question 5

why is finding out the cause of interstitial lung disease important?

Answer 5

• treatment for one cause may be disastrous for another

Question 6

pathogenesis of interstitial lung disease

Answer 6

• epithelial injury leading to fibroblast activation, causing fibrosis
• injury to alveolar epithelial cells (smoke, pollutants)
• activation of inflammatory cells and epithelial and endothelial cells
• release of fibrogenic cytokines and growth factors
• proliferation of fibroblast, causes myofibroblast proliferation leading to fibrosis

Question 7

which are the types of interstitial lung disease?

Answer 7

• exudative

- granulomatous

Question 8

what happens in exudative interstitial lung disease?

Answer 8

• collagen is laid down on the walls
• this traps the exudates
• affects the base of the lungs

Question 9

which areas of the lung does granulomatous interstitial lung disease affect?

Answer 9

• spares the base of the lungs

- affects the upper lobes

Question 10

which are the types of exudative lung disease?

Answer 10

• idiopathic pulmonary fibrosis
• systemic disease like RA, systemic sclerosis
• pneumoconioses

Question 11

which are the granulomatous lung disease?

Answer 11

• sarcoidosis
• extrinsic allergic alveolitis
• pneumoconioses (silicosis)

Question 12

signs and symptoms of ILD

Answer 12

• dyspnoea on exertion
• fatigue
• cough
• clubbing
• systemic symptoms: fever, weight loss
• bilateral end-expiratory crackles
• signs of right heart failure

Question 13

what are the criteria for diagnosis?

Answer 13

• abnormal PFTs with evidence of restriction
• basilar reticular abnormalities with ground-glass appearance on high-resolution CT scans
• lung biopsy of bronchoalveolar lavage showing no features to support an alternative diagnosis

Question 14

which are the more common types of interstitial lung disease?

Answer 14

• idiopathic pulmonary fibrosis
• extrinsic allergic alveolitis
• asbestos related disease

Question 15

which group of patients normally present with IPF?

Answer 15

people in their 40s or 50s

Question 16

which genetic abnormalities are associated with IPF?

Answer 16

• variant of promoter gene that codes for mucin
• mutations in serum surfactant protein C damages type II alveolar epithelial cells
• mutant telomerase

Question 17

pathogenesis of IPF

Answer 17

• trigger for damage to Type I pneumocyte and alveolar capillary endothelium
• acute phase: interstitial oedema/protein exudation into alveoli (fibrin: early membranes - ARDS picture)
• interstitial inflammation (mainly lymphocytes) and type II pneumocyte regeneration
• fibroblastic activity is stimulated by inflammatory cells, epithelium and endothelium cells releasing cytokines and growth factors
• myofibroblasts secrete extracellular matrix
• resistance of fibroblasts to apoptosis
• organisation leading to interstitial fibrosis

Question 18

pathological features of a honeycomb lung

Answer 18

• end-stage chronic interstitial fibrosis
• cystic air spaces with coalesence
• dilated bronchi and alveoli
• septal fibrosis and inflammation
• focal squamous metaplasia
• smooth muscle proliferation round terminal bronchioles

Question 19

commonest causes of honeycomb lung

Answer 19

• idiopathic pulmonary fibrosis
• extrinsic allergic alveolitis
• sarcoidosis

Question 20

complications of IPF

Answer 20

• fibrosis, reducing the pulmonary capillary network, leading to pulmonary hypertension
• RVH
• RHS HF

Question 21

prognosis of IPF

Answer 21

• depends on the extent of the fibrosis

Question 22

what causes extrinsic allergic alveolitis?

Answer 22

• immune reaction to inhaled antigens

- defect in antigen specific T lymphocyte suppressor function

Question 23

types of EAA

Answer 23

• bird fancier’s lung
• animal handlers’ lung
• farmers’ lung
• microbial antigens (includes contaminated rotting crops)

Question 24

what type of HS reaction is EAA?

Answer 24

type III

Question 25

symptoms of EAA

Answer 25

• dyspnoea
• fever
• cough 4-8 hours
  after exposure to antigen, resolving after 12-24 hours

Question 26

what happens if there is repeated exposure to the antigen?

Answer 26

type IV HS reaction

Question 27

pathological features of EAA

Answer 27

• small granulomas
• lymphocytes in the interstitium
• scanty neutrophils, eosinophils, mast cells
• interstitial fibrosis
• rarely honeycomb lung

Question 28

which occupations are more prone to asbestos related disease?

Answer 28

• mining
• refining asbestos
• building industry
• dockyards

Question 29

what does the risk of asbestos disease depend on?

Answer 29

• duration (exposure risk)
• intensity
• type of asbestos exposed to

Question 30

what are the asbestos-related diseases?

Answer 30

• pleural plaques
• pleural effusions
• asbestosis
• malignant mesothelioma
• carcinoma of the lung

Question 31

what material are pleural plaques made of?

Answer 31

collagen

Question 32

what does asbestosis consist of?

Answer 32

• interstitial fibrosis of lungs

- maximal at the lung bases

Question 33

what PFT pattern do patients with asbestosis have?

Answer 33

restrictive

Question 34

what are asbestosis bodies?

Answer 34

long, thin fibres coated with haemosiderin and protein to form brown filaments with a bead or drumstick pattern
- present in sputum