Interstitial and occupational lung disease

Question 1

Broadly, what is interstitial lung disease?

Answer 1

Any disease process that affects the lung interstitium (alveoli and terminal bronchi)
It is therefore a disease that interferes with gas transfer and shows a restrictive lung pattern with symptoms of breathlessness and dry cough

Question 2

What are the three types of ILD?

Answer 2

Acute
Episodic
Chronic - part of systemic disease, exposure to agent, idiopathic

Question 3

What drug can cause ILD?

Answer 3

Methotrexate and nitrofuratonin

Question 4

What is sarcoidosis?

Answer 4

Granulomatous (type 4 sensitivity) disease of unknown cause
Involves the lungs, lymph nodes, joints, liver, skin and eyes
Non-caseating granuloma of unknown aetiology

Question 5

What are some symptoms of acute sarcoidosis?

Answer 5

Erythema nodosum
Bilateral hilar lymphadenopathy
Arthritis
Uveitis
Parotitis
Fever

Question 6

What are some symptoms of chronic sarcoidosis?

Answer 6

Lung infiltrates (alveolitis)
Skin infiltrations
Peripheral lymphadenopathy
Hypercalcaemia

Question 7

What is the differential diagnosis in some suspected having sarcoidosis?

Answer 7

TB, lymphoma, carcinoma, fungal infection

Question 8

How is sarcoidosis diagnosed?

Answer 8

CXR (bilateral hilar lymphadenopathy) CT scan of lungs (peripheral nodular infiltrate)
Tissue biopsy (transbronchial, skin, lymph node), non-caseating granulmona
Restrictive function on pulmonary function test
Blood test: angiotensin converting enzyme (ACE) levels as activity marker (NOT diagnostic test)
Raised calcium
Increased inflammatory markers

Question 9

What is the treatment of sarcoidosis?

Answer 9

Acute: self-limiting usually no treatment
Steroids if vital organs are affected (e.g. impaired lung function, heart, eyes, brain, kidneys)
Chronic: oral steroids
Immunosuppresion (methotrexate, anti-TNF therapy)
Monitor CXR and pulmonary function tests

Question 10

What is erythema nodosum?

Answer 10

Red patches of tender nodules which will fade and bruise

Question 11

What is uveitis?

Answer 11

The anterior chambers of the eye fill up with inflammatory materials causing glaucoma and permanent damage - needs urgent referral to eye clinic
Treated with steroid drips

Question 12

What are the granulomas in sarcoidosis composed of?

Answer 12

Epithelioid histiocytes
Multinucelated giant cells
Lymphocytes
Plasma cells
Fibroblasts
Collagen

Question 13

What is EAA?

Answer 13

Type 3 hypersensitivity (immune complex disposition) reaction to antigens
Aetiology: thermophilic actinomycetes (farmers lung, malt workers, mushroom workers), avian antigens (bird fanciers lung) drugs (gold, blemocycin, sulphasalazine)

Question 14

What are the symptoms and treatment of acute EAA?

Answer 14

Cough, breathlessness, fever, myalgia (symptoms occur several hours after acute exposure)
Pyrexia, crackles (no wheeze), hypoxia
CXR: widespread pulmonary infiltrates
Treatment: oxygen, steroids, antigen avoidance

Question 15

What are the symptoms of chronic EAA?

Answer 15

Repeated low dose antigen exposure over years with progressive breathlessness and cough
Crackles, clubbing unusual
CXR: pulmonary fibrosis in upper zones
Pulmonary function tests: restrictive defect

Question 16

How is chronic EAA diagnosed?

Answer 16

History of exposure, precipitins (IgG antibodies to guilty antigen), lung biopsy if in doubt

Question 17

How is chronic EAA treated?

Answer 17

Remove antigen exposure

Oral steroids if breathless or low gas transfer

Question 18

What can cause IPF?

Answer 18

Aetiology of primary IPF not known
Secondary causes: rheumatoid, SLE (lupus), systemic sclerosis, asbestos, amiodarone, busulphan, belomycin, nitrofuraantoin, methotrexate

Question 19

What is the clinical presentation of IPF?

Answer 19

Progressive breathlessness, dry cough, clubbing, bilateral fine inspiratory crackles
Restrictive defect on PFTs
Bilateral infiltrates on CXR
CT: Reticulondular fibrotic shadowing worse at bases and periphery
Traction bronchiectasis, honey-combing cystic changes
Lung biopsy

Question 20

What is the differential diagnosis if IPF is suspected?

Answer 20

Occupational disease (asbestosis, silicosis), connective tissue disease, left ventricular failure, sarcoidosis, EAA

Question 21

How is IPF diagnosed?

Answer 21

History
Examination
Radiology test (HRCT)

Question 22

What is the pathology of IPF?

Answer 22

Usual Interstitial Pneumonia Pattern (UIP) with heterogenous fibrosis in alveolar walls with fibroblastic foci and the destructino of architecture causing honeycombing with minimal inflammation

Question 23

How is IPF treated?

Answer 23

New antifibrotic drugs can slow down disease progression but is very expensive
Oxygen if hypoxia
Lung transplantation in young patients
Most patients progress within a few years into resp failure, median survival of IPF is 4 years from point of diagnosis

Question 24

What is coal workers pneumoconiosis?

Answer 24

Simple pneumoconiosis - CXR abnormality only - no impairment of lung function
Compicated pneumoconiosis - progressive massive fibrosis, restrictive pattern with breathlessness
Chronic bronchitis - coal dust and smoking

Question 25

What is caplan’s syndrome?

Answer 25

Exposure to coal dust can cause rheumatoid pneumoconiosis (pulmonary nodules, cavitating nodules in the lungs

Question 26

What is silicosis?

Answer 26

15-20 years exposure to quartz
Simple pneumoconiosis - few symptoms, CXR abnormality (egg-shell calcification of hilar nodes)
Chronic silicosis - restrictive pattern, pulmonary fibrosis

Question 27

What are some asbestol related lung disorders?

Answer 27

Pleural disease: benign pleural plaques - asymptomatic
Acute asbestos pleuritis - fever, pain, bloody pleural effusion
Pleural effusion and diffuse pleural thickening - restirctive impairement
Malignant mesothelioma - incurable pleural cancer, presents with chest pain and pleural effusion
Pulmonary fibrosis - diffuse pulmonary fibrosis and restrictive defect, asbestos bodies in sputum
Bronchial carcinoma