Pathology of Restrictive Lung Disease

Question 1

Where does the inflammtory process of the lungs take place?

Answer 1

The interstitium of the lung

Question 2

What is the interstitium of the lung?

Answer 2

It is the connective tissue space around the airways and vessels and the the apce between the basement membranes of the alveolar walls of the capillary endothelial.

Question 3

What makes up the normal alveolar wall?

Answer 3

The alveolar epithelium & interstitial capillary endothelial cell basement membranes are in direct contact.

Question 4

What are the unifying features of lung disease?

Answer 4

• Disease process involves interstitial area of lung
• All of disease processes are diffuse in the lungs and involving much or all of both lung
• All associated with restrictive lung defect on the pulmonary function testing.

Question 5

Why do the lungs become stiff (reduced lung compliance)?

Answer 5

Because we are introducing into the interstitial space some kind of pathological tissue (inflammation and fibrous tissue)

Question 6

What happens to the amount of elastic in interstitial lung disease?

Answer 6

It increases.

Question 7

What does the interstitial fibro-infammatory process do to the lungs?

Answer 7

It prevents them from stretching.

Question 8

What does the reduced elasticity of the lung do to the average lung volume?

Answer 8

It decreases.

Question 9

What does low average lung volume lead to?

Answer 9

It leads to low FEV1 and in turn low FVC

Question 10

Why is the FEV1/FVC ratio generally the same in interstitial lung disease?

Answer 10

Because there is no airflow limitation.

Question 11

What happens to gas exchange as a result of interstitial lung disease?

Answer 11

It reduces because there is a diffusion abnormality.

Question 12

When is there an imbalance in the ventilation/perfusion relationship?

Answer 12

When the pathology affects the small airways.

Question 13

What is the presentations of diffuse lung disease?

Answer 13

SOB on exertion –> (as disease progresses) shortness of breath at rest.
Respiratory Failure - Type 1
Heart failure

Question 14

How does the X-ray or CT scan of diffuse lung disease look?

Answer 14

Abnormal

Question 15

What is an diffuse interstitial lung disease?

Answer 15

They are primarily inflammatory diseases affecting parenchymal part of the lung cause injury within the interstitium of the lung.

Question 16

What are the two types of inflammatory responses?

Answer 16

Acute (sometimes merge into chronic) and chronic

Question 17

Where is emphysema normally found?

Answer 17

In the apex of the upper lobe

Question 18

What happens when emphysema spreads too much?

Answer 18

The lungs get bigger

Question 19

What is an important factor in interstitial lung disease with regards to the inflammatory process leading to fibrosis?

Answer 19

The more likely the process is to lead to fibrosis, the more likely the patient is going to have long term pulmonary difficulties.

Question 20

What is acute inflammatory response injury in the lung referred to as pathologically?

Answer 20

It is referred to as diffuse alveolar damage.

Question 21

What is diffuse alveolar damage related to?

Answer 21

• Trauma
• Chemical injury
• Circulatory Shock
• Drugs
• infection including viruses
• Autoimmune disease
• Radiation

However they can be idiopathic.

Question 22

What is the process of the development of DAD?

Answer 22

Over 1 or 2 days after injury the is a large amount of oedema that develops in the lungs because there is lots of damage to the interstitial of the lungs. Water and plasma proteins leak out and these plasma proteins precipitate on the alveoli forming hyaline membranes after several more days. It takes a few more days for the inflammatory process to develop and more days for fibrosis to follow on from the inflammatory process.

Question 23

What are the histological features of DAD?

Answer 23

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

Question 24

What are examples of a granulomatous chronic inflammatory response in the lung?

Answer 24

Sarcoidosis

Hypersensitivity pneumonitis

Question 25

What is sarcoidosis?

Answer 25

A multi system granulomatous disorder of unknown aetiology

Question 26

What type of hypersensitivity reaction is sarcoidosis?

Answer 26

Type IV - production of granuloma

Question 27

What is the histopathology of sarcoidosis?

Answer 27

• Epihtheliod and giant granulomas
• Necrosis ver unusual
• Little lymphoid infiltrate
• Variable associated fibrosis

Question 28

Why does sarcoidosis rarely proceed to significant fibrosis?

Answer 28

Because there are very little type III reaction or chronic inflammatory reactions.

Question 29

What organs are most involved in sarcoidosis?

Answer 29

Lymph nodes and lungs

Question 30

How is sarcoidosis diagnosed?

Answer 30

Mostly clinically but can be done with imaging

Question 31

What is hypersensitivity pneumonitis characterised by?

Answer 31

Hypersensitivity reaction to organic molecules or to organic antigens.

Question 32

What are common antigens of hypersensitivity pneumonitis?

Answer 32

Birds, animals, fungi and chemicals.

Question 33

What is thermoactinomyces more commonly known as?

Answer 33

Farmers lung

Question 34

What does the presentation of hypersensitivity pneumonitis depend on?

Answer 34

The reactivity of the patient and the dose of antigen that the patient is exposed to

Question 35

What is the histopathology of hypersensitivity pneumonitis?

Answer 35

• immune complex mediated combined Type III and IV hypersensitivity reaction
• soft centriacinar epitheliod granulomatoma
• interstitial pneumonitis
• foamy histiocytes
• upper zone disease

Question 36

What pathological process is taking place in the lungs during idiopathic pulmonary fibrosis?

Answer 36

Usual interstitial pneumonitis

Question 37

Exposure to what products can lead to idiopathic pulmonary fibrosis?

Answer 37

Drugs, asbestos and viruses

Question 38

Ho common is it for severe fibrosis to occur in usual interstitial pneumonitis?

Answer 38

Really common

Question 39

How common is it for granulomatous response to progress to severe fibrosis?

Answer 39

Not common

Question 40

Diffuse Pulmonary fibrosis is a risk factor for what…

Answer 40

Lung cancer