Interstitial and Occupational Lung Disease

Question 1

describe interstitial disease

Answer 1

any disease process affecting lung interstitium (alveoli, terminal bronchi)
interferes with gas transfer
restrictive lung patterns

can be;
acute
episodes
chronic - part of systemic disease, exposure to agents (drug, dust, bird feathers) or idiopathic

Question 2

describe symptoms of restrictive lung disease

Answer 2

breathlessness

dry cough

Question 3

describe sarcoidosis

Answer 3

granulomatous (tpye IV hypersensitivity) disease of unknown cause
multiple system involvement;
common - lungs, lymph nodes, joints, liver, skin, eyes
uncommon - kidneys, brain, nerves, heart

non-caseating granuloma of unknown aetiology - probable infective agent in susceptible individual
imbalance of immune system with type IV (cell mediated) hypersensitivity
less common in smokers

Question 4

describe types of sarcoidosis - acute

Answer 4

erythema nodosum
bilateral hair lymphadenopathy
arthritis 
uveitis, parotitis
fever
self-limiting condition

Question 5

describe types of sarcoidosis - chronic

Answer 5

lung infiltrates (alveolitis)
skin infiltrations 
peripheral lymphadenopathy
hyper-calcaemia 
other organs - renal, myocardial, neurological, hepatitis, splenomegaly -
oral steroids if vital organ effected

Question 6

describe differential diagnosis of sarcoidosis

Answer 6

TB
lymphoma
carcinoma
fungal infection

Question 7

describe tests for sarcoidosis

Answer 7

CXR
high resolution CT - peripheral nodular infiltrate
tissue biopsy - transbronchial, skin, lymph nodes, non caseating granuloma (indication of TB)
pulmonary function - restrictive defect due to lung infiltrates
blood tests;
angiotensin converting enzyme (ACE) level as activity marker (not a diagnostic test)
raised calcium
increased inflammatory markers

Question 8

describe treatment of sarcoidosis - acute

Answer 8

no treatment

steroids if vital organ effected - impaired lung function, heart, eyes, brain, kidneys

Question 9

describe treatment of sarcoidosis - chronic

Answer 9

oral steroids

immunosuppession - azathioprine, methotrexate, anti-TNF therapy)

Question 10

describe hypersensitivity pneumonitis (extrinsic allergic alveolitis)

Answer 10

type III hypersensitivty (immune complex disposition) reacction to antigen lymphocytic alveolitis

caused by;
thermophilic actinomycetes - farmers lung, malt workers, mushroom workers
avian anitgens - bird fanciers lung 
drugs - gold, bleomycin, sulphasalazine
no cause in ~30% cases

Question 11

describe acute sarcoidosis - symptoms, signs, treatment

Answer 11

can be acute or chronic

acute;
cough, breathless, fever, myalgia - symptoms hours after acute exposure

signs - +/- pyrexia, crackles (no wheeze), hypoxia, CXR - widespread pulmonary infiltrates

treatment - oxygen, steroids, antigen avoidance, anti-fibrotic therapy in cases of progressive fibrosis (prifenidone, nintedanib)

Question 12

describe chronic sarcoidosis - symptoms, signs, tests, diagnosis and treatment

Answer 12

chronic - repeated low does antigen exposure over time (years)

symptoms - progressive breathlessness and cough

signs - crackles, clubbing unusual

tests - CXR shows pulmonary fibrosis (upper zones), Pulmonary function tests - restrictive defect (low FEV1 and FVC –> high or normal ratio, low gas transfer - TLCO)

diagnosis - history of exposure, precipitins (IgG antibodies to guilty antigen), lung biopsy if not

treatment - remove antigen exposure, oral steroids if breathless or low gas transfer

Question 13

describe idiopathic pulmonary fibrosis (Cryptogenic fibrosing alveolitis)

Answer 13

most common interstitial lung disease 
idiopathic disease;
imbalance of fibrotic repair system
? related to gastric reflux
not an inflammatory disease
more common in smokers 

secondary causes;
rheumatoid, SLE, systemic sclerosis, asbestos
drugs - amiodarone, busulphan, bleomycin, penicillamine, nitrofurantoin, methotrexate

pathology - usual interstitial pneumonia pattern (UIP), heterogenous fibrosis in alveolar walls with fibroblastic foci and destruction of architecture causing honeycombing. Inflammation minimal

Question 14

describe clinical presentation of IPF

Answer 14

progressive breathlessness over several years, dry cough

finger clubbing, bilateral fine inspiratory crackles

Question 15

describe tests for IPF

Answer 15

pulmonary function test - restrictive defect - reduced lung volumes and low gas transfer
CXR - bilateral infiltrates
CT - reticulondular fibrotic shadowing, worse at lung bases and periphery, traction bronchiectasis, honeycombing cystic changes
lung biopsy - not necessary if CT diagnostic

Question 16

describe differential diagnosis of IPF

Answer 16

exclude occupational disease (asbestos, silicosis)
connective tissue disease (RhA, scleroderma, siogrens disease, SLE)
left ventricular failure
sarcoidosis
extrinsic allergic alveolitis

always ask about occupation, pets and drug history

Question 17

describe treatment of IPF

Answer 17

steroids and immunosuppressants do not change course of disease
new antibiotics - pirfenidone and nintedanib - slow down disease progression (expensive and side effects)
antifibrotic therapy does no reverse fibrosis but slows progression
oxygen is hypoxic
lung transplant in young patients

many patients progress to respiratory failure, 4 years survival rate from diagnosis

Question 18

describe coal workers pneumoconiosis

Answer 18

simple pneumoconiosis - CXR abnormality only - egg-shell calcification of hilar nodes (no impairment of lung function, associated with COPD)
complicated pneumoconiosis - progressive massive fibrosis. Restrictive pattern with breathlessness
chronic bronchitis (coal dust and smoking)
Caplan’s syndrome - rheumatoid, pneumoconiosis (pulmonary nodules)

Question 19

describe silcosis

Answer 19

15-20 years exposure to quartz (mining, foundry workers, glass workers, boiler workers)
simple pneumoconiosis
chronic silicosis - restrictive pattern, pulmonary fibrosis

Question 20

describe asbestos - related lung disorders - pleural disease

Answer 20

benign pleural - asymptomatic
acute asbestos pleuritis - fever, pain, bloody pleural effusion (benign condition)
pleural effusion and diffuse pleural thickening - restrictive impairment
malignant mesothelioma - incurable pleural cancer. Presents with chest pain and pleural effusion. No treatment

Question 21

describe asbestos - related lung disorders - pulmonary fibrosis

Answer 21

asbestosis;
heavy prolonged exposure
diffuse pulmonary fibrosis and restrictive defect
asbestos bodies in sputum 
asbestos fibres in lung biopsy

Question 22

describe asbestos - related lung disorders - bronchial carcinoma

Answer 22

asbestos multiplies risk in smokers