Asbestosis related lung disease

Question 1

What is asbestosis?

Answer 1

Long-term inflammation + scarring of the lungs caused by inhalation of asbestos fibres
(asbestos-related interstitial fibrosis)

Question 2

What is mesothelioma?

Answer 2

aggressive tumour of mesothelial cells, usually occurs in the pleura (90%)+ peritoneum, pericardium or testes
Asbestos is the main causative agent
POOR PROGNOSIS

Question 3

What is the mesothelium?

Answer 3

Thin epithelium that lines several body cavities including the pleura, peritoneum, mediastinum + pericardium

Question 4

Describe the aetiology of asbestosis

Answer 4

Asbestos was used in building trade hence always ask about OCCUPATION in resp hx: shipyard workers
Degree of exposure is related to degree of pulmonary fibrosis.
Inflammation gradually causes mesothelial plaques in the pleura
Increases risk of bronchial adenocarcinoma + mesothelioma

Question 5

What are the 3 types of asbestosis?

Answer 5

Chrysotile (white asbestos): least fibrogenic.
Crocidolite (blue asbestos): most fibrogenic.
Amosite (brown asbestos) has intermediate fibrogenicity.

Question 6

Describe the aetiology of mesothelioma

Answer 6

Associated with occupational exposure to asbestos
90% report exposure to asbestos, but only 20% of pts have pulmonary asbestosis.
Malignant pleural mesothelioma rarely spreads to distant sites but most pts present with locally advanced disease.

Question 7

List 10 symptoms of mesothelioma

Answer 7

SOB
Chest pain (dull, diffuse, developing)
Weight loss 
Dry cough 
Fatigue 
Fever 
Night sweats 
Abdo pain 
Bone pain (but doesn't usually spread to bone)  
Sometimes, bloody sputum; if tumour invades blood vessels

Question 8

Give 2 signs of asbestosis

Answer 8

Clubbing (only advanced asbestosis)

Fine end-inspiratory crackles: initially heard at bases + increases with progression of disease

Question 9

List 6 signs of mesothelioma

Answer 9

Finger clubbing: due to underlying asbestosis (pulmonary fibrosis)
Diminished breath sounds + dullness to percuss (Recurrent pleural effusions)
Signs of mets: Lymphadenopathy, Hepatomegaly, bone tenderness
Abdo pain/ obstruction (peritoneal malignant mesothelioma)
Occasional palpable chest wall mass
Can rarely cause pneumothorax

Question 10

What investigations should be performed for asbestosis?

Answer 10

Hx + exam
CXR: reticular-nodular shadowing/ pleural plaques
Pulmonary function tests: mix of restrictive + obstructive changes

Question 11

What is the latent period between exposure and development of mesothelioma?

Answer 11

Up to 50 yrs (30 – 50 yrs after)

Question 12

What investigations should be performed for mesothelioma?

Answer 12

CXR
CT
MRI + PET: degree of invasion + location
Pleural fluid (Thoracentesis): cytological analysis
Pleural biopsy: diagnostic
Cervical mediastinoscopy: spread to mediastinal lymph N

Question 13

What is seen on CXR in mesothelioma?

Answer 13

Unilateral pleural effusion
Irregular pleural thickening
Reduced lung volumes +/- parenchymal changes related to asbestos exposure (e.g., lower zone linear interstitial fibrosis)

Question 14

What is the diagnosis of mesothelioma usually based on?

Answer 14

Histology, usually following a thoracoscopy (pleural biopsy): often done post-mortem
Biopsy of the tumour can be immunostained with a stain that reacts with CALRETININ

Question 15

How does mesothelioma usually spread?

Answer 15

Usually spread to pleural cavity then lung + hilar lymph nodes

Question 16

What is seen on CT chest in mesothelioma?

Answer 16

Pleural thickening +/- discrete pleural plaques
Pleural effusions
Enlarged hilar +/- mediastinal lymph nodes
Chest wall invasion

Question 17

What does the spectrum of asbestos-related thoracic diseases comprise of?

Answer 17

Benign pleural effusion, pleural plaques, diffuse pleural thickening, rounded atelectasis, asbestosis, mesothelioma + lung cancer.