Pathology of restrictive lung disease

Question 1

What is the interstitium ?

Answer 1

The connective tissue space around the airways and vessels and the space between the basement membrane of the alveolar walls

Question 2

What is the relationship between the normal alveolar wall and most of the alveolar epithelial (pneumocyte) & interstitial capillary endothelial cell basement membranes ?

Answer 2

They are in direct contact

Question 3

What are the characteristics of Restrictive – Diffuse - Interstitial Lung Disease ?

Answer 3

Reduced lung compliance:
- stiff lungs
Low FEV1 & low FVC but FEV1/FVC normal ratio
Reduced gas transfer (Tco or Kco):
- diffusion abnormality
Ventilation/perfusion imbalance:
- when small airways affected by pathology

Question 4

Is there airflow limitation in restrictive lung disease ?

Answer 4

No

Question 5

What are the clinical presentations for restrictive lung disease ?

Answer 5

Discovery of abnormal CXR or CT scan 
Dyspnoea:
    - SOB on exertion
    - SOB at rest 
Respiratory failure- type 1
Heart failure

Question 6

What are the outcomes of Parenchymal (Interstitial) Lung Injury ?

Answer 6

Acute inflammation (can develop into chronic response in rare circumstances) or Chronic inflammation

Question 7

What is DAD ?

Answer 7

Diffuse alveolar damage

Question 8

What is DAD associated with ?

Answer 8

Major trauma 
Chemical injury/ toxic inhalation
Circulatory shock 
Drugs 
Infection including viruses:
    - influenza
    - SARS COV2
Autoimmune disease
Radiation 
But it can be idiopathic

Question 9

What are the exudative stages of DADS ?

Answer 9

Oedema and Hyaline membranes
Oedema - Vessels become massively leaky - more so than in a normal response
Hyaline membranes - lots of proteins

Question 10

What are the histological features of DADS ?

Answer 10

Protein rich oedema
 Fibrin
Hyaline membranes
Denuded basement membranes
Epithelial proliferation
Fibroblast proliferation
Scarring- interstitium and airspaces

Question 11

What is the commonest interstitial lung disease that you will encounter ?

Answer 11

Sarcoidosis

Question 12

What is sarcoidosis ?

Answer 12

A multisystem granulomatous disorder of unknown aetiology

Question 13

What pathology does sarcoidosis have ?

Answer 13

That of a type 4 hypersensitivity reaction -> granuloma

Question 14

What is the histopathology of sarcoidosis ?

Answer 14

Epithelioid and giant cell granulomas
Necrosis/ caseation very unusual
Little lymphoid infiltrate
Variable associated fibrosis

Question 15

What is the presentation of sarcoidosis ?

Answer 15

Young adults
    - Acute arthralgia
    -  erythema nodosum
    - Bilateral hilar lymphodenopathy
 Incidental abnormal CXR or CT scan- no symptoms
SOB, cough and abnormal CXR

Question 16

Do most patients with sarcoidosis reach end stage fibrotic lung disease ?

Answer 16

No

Question 17

What is the diagnosis of sarcoidosis ?

Answer 17

Clinical findings
Imaging findings
Serum, Ca++ and ACE
Biopsy

Question 18

What are the hypersensitivity pneumonitis antigens ?

Answer 18

Thermophilic actinomycetes 
      - micropolyspora faeni 
      - thermoactinomyces vulgaris 
Bird/ animal proteins- faeces, bloom
Fungi- aspergillus spp
Chemicals 
Others

Question 19

What is the acute presentation for Hypersensitivity Pneumonitis ?

Answer 19

Fever, dry cough, myalgia
Chills 4-9 hours after Ag exposure
Crackles, tachypnoea, wheeze
Precipitating antibody

Question 20

What is the chronic presentation of hypersensitivity pneumonitis ?

Answer 20

Insidious
Malaise, SOB, cough
Low grade illness
Crackles and some wheeze
(Can lead to respiratory failure 
Gas transfer low
History important)

Question 21

What type of hypersensitivity causes Hypersensitivity Pneumonitis ?

Answer 21

Immune complex mediated combined Type III and Type IV Hypersensitivity reaction

Question 22

What is the histopathology of hypersensitivity pneumonitis ?

Answer 22

Soft centiacinar epitheliod granulomata Interstitial pneumonitis
Foamy histiocytes
Bronchiolitis obliterans
Upper zone disease

Question 23

What are the causes of Usual interstitial pneumonitis ?

Answer 23

Connective tissue diseases - scleroderma and rheumatoid disease
Drug reaction
Industrial exposure
Idiopathic/cryptogenic reasons

Question 24

What is the histopathology of UIP ?

Answer 24

Patchy interstitial chronic inflammation
Type II pneumocyte hyperplasia
Smooth muscle and vascular proliferation
Evidence of old and recent injury:
       - temporal heterogenicity 
      - spatial heterogenicity 
Proliferating fibroblastic foci

Question 25

What are Proliferating Fibroblastic Foci ?

Answer 25

Nodules of fibrous tissue in the walls of the alveoli, reflect the severity of the disease

Question 26

Who usually suffers from Idiopathic Pulmonary Fibrosis ?

Answer 26

Elderly >50

M>F

Question 27

What is the clinical presentation of Idiopathic Pulmonary Fibrosis ?

Answer 27

Dyspnoea, cough

Basal crackles, cyanosis, clubbing

Question 28

What is the prognosis for Idiopathic Pulmonary Fibrosis ?

Answer 28

Poor prognosis

Usually dead within 5 years

Question 29

What will you see in the chest X-ray for someone with Idiopathic Pulmonary Fibrosis ?

Answer 29

Basal/posterior, diffuse infiltrates, cysts, ‘ground glass’

Question 30

What is UIP Basal and posterior fibrosis with honeycombing often complicated with ?

Answer 30

Peripheral adenocarcinoma

Question 31

Describe the airway flow in interstitial lung disease ?

Answer 31

Normal air flow, diffusion is altered