4- interstitial & occupational lung diseases

Question 1

what is interstitial disease?

Answer 1

• any disease affecting lung interstitium (alveoli themselves, deep in bronchial tree)
• interferes with gas transfer

Question 2

what is result of interstitial disease on pulmonary function tests?

Answer 2

restrictive pattern (may have airway obstruction too)

Question 3

what are the 4 different broad categories of ILD?

Answer 3

1. group where we know the cause e.g. drug or associations
2. idiopathic interstitial pneumonia = group of conditions e.g. IPF. get either inflammation or impaired mechanisms causing lung disease
3. granulomatous ILDs e.g sarcoidosis
4. other forms = random mix, most are rare

Question 4

what is sarcoidosis?

Answer 4

• granulomatous (type 4 hypersensitivity) disease of unknown cause
• multi-system involvement
• non-caseating granuloma of unknown aetiology: probable infective agent in susceptible individual. Imbalance of immune system with excessive type 4 (cell mediated) hypersensitivity
  →less common in smokers

Question 5

what are presentations of acute sarcoidosis?

Answer 5

• painful nodules on shins of legs (erythema nodosum)
• bilateral hilar lymphadenopathy
• painful red eyes due to uveitis, fever

Question 6

what are presentations of chronic sarcoidosis?

Answer 6

doesn’t settle without treatment, goes on for years - risk of lung scarring due to persistent inflammation leading to fibrosis. can get impaired calcium metabolism = hypercalcaemia, important to screen them for other organ involvements

= often presents in generic way with a lot of symptoms that can be other diseases so important to rule out things like TB, lymphoma, carcinoma, fungal infections

Question 7

what are investigations for sarcoidosis?

Answer 7

• basic chest x-ray (shows enlarged lymph nodes)
• CT scan = gives more detail e.g scarring or lung involvement
• blood test = renal function, liver function, calcium levels, ACE levels (if high good marker for disease treating with), inflammatory markers

Question 8

what is treatment for acute or chronic sarcoidosis?

Answer 8

acute = often self limiting and no treatment needed

chronic = treat with steroids and immunosuppression (azathioprine, methotrexate, anti-TNF treatment)

Question 9

what is hypersensitivity bit of hypersensitivity pneumonitis?

Answer 9

type 3 hypersensitivity = immune complex deposition reaction. reaction to antigen lymphocytic alveolitis

complex deposited in lungs causing inflammation including type 3 + type 4 hypersensitivity

Question 10

what are the causes of hypersensitivity pneumonitis?

Answer 10

things that cause hypersensitivity reaction like

• fungal stuff = Thermophilic actinomycetes (farmers lung, malt workers, mushroom workers, other moulds)
• avian antigens (bird fanciers lung)
• drugs (gold, bleomycin, sulphasalazine)

Question 11

what is very important for diagnosis of hypersensitivity pneumonitis?

Answer 11

history = some seemingly random parts of social history can be very important (no cause is identified in 30% of HP cases)

Question 12

what are some classical signs and symptoms of acute hypersensitivity pneumonitis?

Answer 12

acute:cough, breathless, fever, myalgia = classic symptoms come on several hours after exposure (not immediate like type 1). it’s alveolar problems so not wheezy (that’s airways disease)

signs = pyrexia, crackles, hypoxia (doesn’t usually have finger clubbing!)

Question 13

what makes hypersensitivity pneumonitis chronic?

Answer 13

repeated low dose antigen exposure over years = progressive breathlessness + cough

Question 14

what is treatment for acute hypersensitivity pneumonia?

Answer 14

• Treatment: oxygen, steroid and antigen avoidance = Antifibrotic therapy in cases of progressive fibrosis (Nintedanib)

Question 15

what investigations do you do for hypersensitivity pneumonia?

Answer 15

• can do specific blood test (IgG for specific think you think causing)
• chest x-ray to check for pulmonary fibrosis (common in upper zone)
• pulmonary function test = shows restrictive defect

Question 16

what is important takeaway point about IPF that differs from other ILDs?

Answer 16

NOT inflammatory! - it just involves fibrosis = pulmonary scarring with no inflammation, makes tricky to treat and

Question 17

what are other differential diagnoses of pulmonary fibrosis? (to consider when diagnosing IPF)

Answer 17

• rheumatoid, SLE, systemic sclerosis, asbestos
• drugs with pulmonary fibrosis side effect - amiodarone, busulphan, bleomycin, penicillamine, nitrofurantoin, methotrexate

Question 18

what are characteristic clinical signs of IPF?

Answer 18

fibrosis + finger clubbing = more likely to be IPF (as others don’t have finger clubbing)
- bilateral fine inspiratory crackles

Question 19

what is found on on chest x-ray and CT scan of IPF?

Answer 19

• CxR - bilateral infiltrates;
• CT scan - reticulonodular fibrotic shadowing, worse at the lung bases, and periphery. Traction bronchiectasis (dilated and thickened bronchi). Honey-combing cystic changes. (clusters of advanced fibrosis)

Question 20

is lung biopsy always necessary for IPF?

Answer 20

no, CT scan most important - if CT atypical then might do lung biopsy

Question 21

what would a typical biopsy for IPF show?

Answer 21

Usual Interstitial Pneumonia pattern (UIP) heterogenous fibrosis in alveolar walls with fibroblastic foci and destruction of architecture causing honeycombing. Inflammation is minimal

Question 22

what is the treatment for IPF?

Answer 22

tricky treatment as immunosuppressants + steroids don’t work as no inflammation
- there are some new antifibrotic drugs (pirfenidone + nintedanib) but they are very expensive with lots of side effects and don’t reverse fibrosis just slow progression

• if young enough can do lung transplant but most over 65 so hard diagnosis with only a few years to live

Question 23

what is a complicated pneumoconiosis?

Answer 23

progressive massive fibrosis that would grow and engulf the lungs (rare but serious) = breathlessness

Question 24

what lung diseases can asbestos cause?

Answer 24

pleural diseases = affecting pleura (layer)

1. Benign pleural plaques - fibrosis of plaque = asymptomatic.from previosu asbestosis exposure
2. Acute asbestos pleuritis - fever, pain, bloody pleural effusion
3. Pleural Effusion and Diffuse pleural thickening - restrictive impairment = no treatment
4. Malignant Mesothelioma - incurable pleural cancer. still fairly common. Presents with chest pain and pleural effusion. No available treatment - fatal within two years.

• pulmonary fibrosis = asbestosis
• bronchial carcinoma

Question 25

what is defining difference between asbestosis and IPF?

Answer 25

asbestosis doesn’t develop as quickly as IPF

Question 26

why is upper lobes commonly more affected than lower lobes in lung diseases?

Answer 26

upper lobe affected more than lower as inhalation disease (inhale more in upper lobes)

Question 27

what are the 2 forms of asbestosis?

Answer 27

1. Serpentine (curved) – relatively safe = Get stuck in upper airways and cleared
2. Straight (amphibole) – highly dangerous = More aerodynamic – travel further into lung, penetrate epithelium and get into interstitium

• Once phagocytosed – induce inflammation and stimulate fibrosis