Pathology of Restrictive Lung Diseases

Question 1

What is the other name for restrictive lung disease?

Answer 1

Interstitial lung disease

Question 2

What is the lung interstitium?

Answer 2

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

Question 3

What do interstitial lung diseases reduce?

Answer 3

Reduce compliance (without the loss of elastic tissue) and gas exchange

Question 4

In interstitial lung disease, is compliance reduced in inspiration or expiration and why?

Answer 4

reduced compliance on inspiration is caused by fibrous tissue forming as a result of the inflammation

Question 5

Explain what you would expect to see in the FEV1, FVC and FEV1/FVC ratio in a patient with interstitial lung disease

Answer 5

Low FEV1 & Low FVC but the FEV1/FVC ratio is normal

Question 6

What is the main symptom of restricted lung disease?

Answer 6

Dyspnoea

Question 7

What happens in the acute phase of interstitial lung disease?

Answer 7

diffuse alveolar damage

Question 8

What are the steps in interstitial lung disease?

Answer 8

Diffuse alveolar damage

oedema (protein rich and watery)

Formation of hyaline membranes

Interstitial inflammation and interstitial fibrosis

Question 9

What is the hyaline membrane?

Answer 9

a layer of plasma protein precipitate that internally lines the alveoli

Question 10

What is sarcoidosis?

Answer 10

One of the chronic responses to interstitial lung disease

Question 11

What type of disorder is sarcoidosis?

Answer 11

a multisystem type 4 hypersensitivity granulomatous disorder

Question 12

Describe the histopathology of sarcoidosis

Answer 12

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

Question 13

What demographic is most commonly affected by sarcoidosis?

Answer 13

young adults, F>M

Question 14

What is the incidence of sarcoidosis in the UK?

Answer 14

around 3-4/100,000 in the UK

Question 15

Where in the world is sarcoidosis incidence low?

Answer 15

low in equatorial regions- sarcoidosis is a disease of temperate climates

Question 16

How does sarcoidosis present?

Answer 16

• Young adult
• Acute arthralgia
• Erythema nodosum
• Bilateral hilar lymphadenopathy
• Incidental abnormal CXR or CT scan - no symptoms. Look for massive enlargement of the hilar lymph nodes (granulomatous inflammation)
• Can present as SOB & cough or it can be asymptomatic.

Question 17

how is sarcoidosis managed?

Answer 17

Sarcoidosis is often time limiting and does not require any therapeutic intervention.

Question 18

Name the two clinical findings which, alongside the history and examination, are diagnostic of sarcoidosis

Answer 18

Raised serum Ca+ and ACE

Question 19

What is hypersensitivity pneumonitis?

Answer 19

A hypersensitivity reaction to organic molecules/antigens

Question 20

List some of the organic molecules that can cause hypersensitivity pneumonitis

Answer 20

1. Thermophilic actinomycetes (farmers lung)
2. Bird/ animal proteins e.g. faeces
3. Fungi (e.g. aspergillus)
4. Chemicals

Question 21

How does hypersensitivity pneumonitis present?

Answer 21

highly variable
can present like an acute pneumonia but it is more common for it to have a more chronic presentation with gradually decreasing pulmonary function

Question 22

What are the inflammatory process associated with hypersensitivity pneumonitis driven by?

Answer 22

combined Type III and Type IV Hypersensitivity

Question 23

What are the type 3 and type 4 hypersensitivities responsible for individually?

Answer 23

The type 4 reaction results in the granuloma formation

type three reaction results in the chronic interstitial inflammatory process (pneumonitis)

Question 24

How do the hypersensitivity pneumonitis granulomas differ from sarcoidosis granulomas?

Answer 24

hypersensitivity pneumonitis granulomas are soft, diffuse, surrounded by an inflammatory infiltrate, centriacinar & epithelioid in nature

Question 25

Other than the soft granulomas, what are the 3 other histological features of hypersensitivity pneumonitis?

Answer 25

• Interstitial pneumonitis
• Foamy histiocytes
• Bronchiolitis obliterans

Question 26

Where in the lungs would hypersensitivity pneumonitis affect most significantly and why?

Answer 26

Upper zones (because it is caused by inhaled antigens)

Question 27

What is usual interstitial pneumonitis?

Answer 27

Patchy interstitial inflammation with type 2 pneumocyte hyperplasia, proliferative fibroblastic foci and smooth muscle & vascular proliferation

Question 28

What are the causes of usual interstitial pneumonitis?

Answer 28

• Connective tissue diseases; esp. scleroderma and rheumatoid disease
• Drug reaction
• Post infection
• Industrial exposure - asbestos
• Most are idiopathic

Question 29

What demographic is affected by idiopathic pulmonary fibrosis?

Answer 29

Elderly >50

M>F

Question 30

How does idiopathic pulmonary fibrosis present?

Answer 30

• dyspnoea, cough,

- basal crackles, cyanosis, clubbing

Question 31

What CXR findings would you expect in a patient with idiopathic pulmonary fibrosis?

Answer 31

• Basal/posterior pathology
• Diffuse infiltrates
• Cysts
• ‘Ground glass ’ appearance