Restrictive Lung Disease - Pathology

Question 1

What is the interstitium of the lung?

Answer 1

The connective tissue space around the airways and vessels, and the space between the basement membranes of the alveolar walls.

Question 2

What are the arrangement of cells in a normal alveolar wall?

Answer 2

Most of the alveolar epithelial and interstitial capillary endothelial cell basement membranes are in direct contact.

Question 3

What are the signs of interstitial lung disease?

Answer 3

Reduced lung compliance - stiff lungs.
Low FEV1 and FVC, but normal FEV1/FVC.
Reduced gas transfer (Tco and Kco) - diffusion abnormality.
V/Q imbalance - small airways affected.

Question 4

What is the presentation for diffuse lung disease?

Answer 4

Abnormal CXR or CT.
Presents with dyspnoea.
SOB on exertion (and at rest as the disease progresses).
Respiratory failure (Type I).
Heart failure.

Question 5

What is the evolution of DAD?

Answer 5

Oedema - first few days.
Increased hyaline membrane production.
Proliferation - interstitial inflammation and interstitial fibrosis occurs, after a week.

Question 6

What is DAD associated with?

Answer 6

Major trauma.
Chemical injury / toxic inhalation.
Circulatory shock.
Drugs.
Infection (viral - influenza, COVID-19).
Autoimmune disease.
Radiation.
Idiopathy.

Question 7

What are the histological features of DAD?

Answer 7

Protein rich oedema.
Fibrin.
Hyaline membranes.
Denuded basement membranes.
Epithelial and fibroblast proliferation.
Scarring of interstitium and airspaces.

Question 8

What is the histopathology of sarcoidosis?

Answer 8

Epithelioid and giant cell granulomas.
Necrosis and caseation (very unusual).
Little lymphoid infiltrate.
Variable associated fibrosis.

Question 9

What is the incidence of sarcoidosis?

Answer 9

Common in young adults (F>M).
Higher in African-Americans.
Low in equatorial regions.
A disease of temperate climates.

Question 10

What organs are involved in sarcoidosis?

Answer 10

Lymph nodes - ~100%.
Lung - >90%.
Spleen - 75%.
Liver - 70%.
Skin / eyes / skeletal muscle - 50%.
Bone marrow - 20%.
Salivary glands - up to 50%.

Question 11

What is the typical presentation of sarcoidosis?

Answer 11

A young adult with acute arthralgia, erythema nodosum, and bilateral hilar lymphadenopathy.
Incidental abnormal CXR or CT.
SOB and cough.

Question 12

What is the progression and treatment of sarcoidosis?

Answer 12

Resolves after 2 years.
Symptoms may persist or progress.
Treatment - corticosteroids.

Question 13

What does lymph node sarcoidosis cause?

Answer 13

Non-caseating epithelioid granulomas.

Question 14

What is the diagnosis of sarcoidosis?

Answer 14

Clinical and imaging findings.
Serum Ca++ and ACE.
Biopsy.

For historical interest -
Kveim test (~60% +ve).
Tuberculin test.

Question 15

What are the antigens responsible for HP?

Answer 15

Thermophilic actinomycetes.
Bird and animal proteins (faeces, bloom).
Aspergillus spp.
Chemicals.

Question 16

What is the acute presentation of HP?

Answer 16

Fever, dry cough, myalgia.
Chills.
Crackles, tachypnoea, wheeze.

Question 17

What is the chronic presentation of HP?

Answer 17

Insidious.
Malaise, SOB, cough.
Low grade illness.
Crackles and some wheeze.

Question 18

What is the progression of HP?

Answer 18

Respiratory failure.
Low gas transfer.

Question 19

What is the histopathology of HP?

Answer 19

Type III and IV hypersensitivity.
Soft centriacinar epithelioid granulomata.
Interstitial pneumonitis.
Foamy histiocytes.
Bronchiolitis obliterans.
Upper zone disease.

Question 20

What are the causes of UIP?

Answer 20

CT diseases (scleroderma, rheumatoid disease).
Drug reaction.
Post infection.
Asbestos.
Idiopathic - IPF, CFA.

Question 21

What is the histopathology of UIP?

Answer 21

Patchy interstitial chronic inflammation.
Type II pneumocyte hyperplasia.
Smooth muscle and vascular proliferation.
Evidence of old and recent injury.
Proliferating fibroblastic foci.

Question 22

What is IPF, and its signs and symptoms?

Answer 22

Pathology - UIP.
Typically affects >50yr olds (M>F).

Signs - basal crackles, cyanosis, clubbing.
Symptoms - dyspnoea, cough, restrictive PFTs, reduced gas transfer.

Question 23

What are the CXR findings, progression, and prognosis of IPF?

Answer 23

CXR - basal/posterior, diffuse infiltrates, cysts, ‘ground glass’.
Progression - most dead in 5 years.
Prognosis - some fulminant / steroid responsive.

Question 24

What are the chronic responses to interstitial lung injury?

Answer 24

UIP - IPF, CFA, CT diseases, drugs, asbestos, viruses.
Granulomatous responses - sarcoidosis, HP.
Other responses - NSIP, COP, smoking-related fibrosis, asbestos, silicosis.

All result in fibrosis or end-stage honeycomb lung.

Question 25

What does end-stage lung fibrosis cause?

Answer 25

Hypoxia, SOB, and fatigue.
Limits physical activity.