Diffuse Parenchymal Lung Disease

Question 1

What is the pathophysiology in parenchymal lung disease?

Answer 1

Lung interstitium becomes expanded by an inflammatory cell infiltrate (pneumonitis). This impairs gas exchange and causes breathlessness.

Question 2

What is this a presentation of?

Dyspnoea on exertion, non-productive cough, abnormal breath sounds, abnormal CXR, restrictive pulmonary spirometry.

Answer 2

Diffuse parenchymal lung disease

Question 3

What are the known causes of diffuse parenchymal lung disease?

Answer 3

1. Occupational/environmental (asbestosis, silicosis, coal worker)
2. Drugs - nitrofurantoin, amiodarone, sulfasalazine
3. Hypersensitivity reactions
4. Infections - TB, fungal, viral
5. GORD

Question 4

Which systemic disorders is diffuse parenchymal lung disease associated with?

Answer 4

1. Sarcoidosis
2. RA
3. SLE, connective tissue disease, Sjogren’s syndrome
4. UC, autoimmune thyroid disease, renal tubular acidosis

Question 5

What is the treatment for idiopathic pulmonary fibrosis?

Answer 5

Supportive, oxygen, high dose steroids, palliative care.

Question 6

What is the work-up for a suspected diffuse parenchymal lung disease?

Answer 6

1. Meticulous history including occupational and environmental exposure in detail.
2. CXR may show reticular-nodular shadows
3. High resolution CT
4. Lung biopsy for histological examination is sometimes needed for diagnosis but is not first line.

Question 7

What are the long-term complications of diffuse parenchymal lung disease?

Answer 7

1. Cor pulmonale
2. Fibrosis of the lung tissue causes obliteration of pulmonary arterioles - gradual development of pulmonary hypertension