Idiopathic pulmonary fibrosis

Question 1

What is idiopathic pulmonary fibrosis?

Answer 1

Idiopathic pulmonary fibrosis (IPF) is a rare, chronic, life-threatening disease that manifests over several years and is characterised by the formation of scar tissue within the lungs and progressive dyspnoea.

• It is the most common interstitial lung disease among the idiopathic interstitial pneumonias
• which share clinical features of shortness of breath, diffuse pulmonary infiltrates on imaging, and varying degrees of inflammation, fibrosis, or both on lung biopsy

Question 2

What is the aetiology of idiopathic pulmonary fibrosis?

Answer 2

The cause of IPF is not known.

• A possible theory is that an unidentified insult causes damage to the alveolar epithelium, endothelium, and basement membrane.
• Cigarette smoke, organic or metal dust, gastro-oesophageal reflux disease (GORD), diabetes, and infection have each been associated with IPF; however, the exact inciting exposure or exposures remain unknown

Question 3

What is the genetic form of idiopathic pulmonary fibrosis?

Answer 3

familial pulmonary fibrosis (FPF)

• This condition is indistinguishable from its sporadic form, but it afflicts patients at a younger age (mean age at diagnosis is 55 to 60 years)
• accounts for 0.5% to 3.7% of cases of IPF

Question 4

Name some risk factors for idiopathic pulmonary fibrosis?

Answer 4

• family history
• cigarette smoking
• advanced age
• male sex

weak:

• organic and inorganic dust exposure
• GORD
  
  • presumably through injury induced by acid aspiration
• infection
  
  • viral infections: hepatitis C, adenovirus, cytomegalovirus, EBV
• diabetes

Question 5

Summarise the epidemiology of idiopathic pulmonary fibrosis?

Answer 5

The precise incidence and prevalence of IPF are not known

• prevalence in the US has been estimated to be between 14.0 and 42.7 cases per 100,000 people
• prevalence increases with advancing age
• Approx. 2/3 of patients with IPF are over 60 years of age at the time of presentation
• with a mean age at diagnosis of between 60 and 70 years

Question 6

What are the presenting symptoms of idiopathic pulmonary fibrosis?

Answer 6

• dyspnoea
  
  • on exertion
  • progressive
• cough
  
  • non-productive
  • can be severe
  • non-responsive to antitussives
• weight loss
• fatigue
• malaise

Question 7

What are the signs of idiopathic pulmonary fibrosis O/E?

Answer 7

• Creps O/A
  
  • End-expiratory
  • basilar crackles
• clubbing

Question 8

What are some primary investigations for ?idiopathic pulmonary fibrosis?

Answer 8

• CXR
  
  • = basilar, peripheral, bilateral, asymmetrical, reticular opacities
• high-resolution CT (HRCT)
  
  • ​Should be ordered in all patients with a suspected diagnosis of IPF
  • = basilar- and subpleural-predominant areas of increased reticulation, honeycombing, and possible traction bronchiectasis or bronchiolectasis
  • Can increase the level of diagnostic confidence for IPF and, in certain situations, obviate the need for surgical lung biopsy

bloods:

• anti-nuclear antibodies (by immunofluorescence)
  
  • Mildly elevated titres may occur in 10% to 20% of patients with IPF.
  • Titres of >1:160 suggest the possibility that a collagen vascular disease might be responsible for the interstitial lung disease
• rheumatoid factor
  
  • ​see above
• anti-cyclic citrullinated peptide
  
  • The presence of circulating anti-cyclic citrullinated peptide antibodies suggests that a collagen vascular disease might be responsible for the interstitial lung disease.
• myositis panel
  
  • The presence of myositis-specific antibodies suggests that a collagen vascular disease might be responsible for the interstitial lung disease.

Question 9

What are some possible secondary investigations for ?idiopathic pulmonary fibrosis?

Answer 9

• pulmonary function tests
  
  • restrictive changes
  • Restrictive: reduced forced vital capacity, reduced total lung capacity.
  • supports diagnosis
• surgical lung biopsy
  
  • ​A crucial component in the evaluation of patients in whom the history, clinical evaluation, and high-resolution CT findings do not support a clear diagnosis of IPF.
  • = fibrosis, areas of normal lung next to areas of honeycombing; areas of more active scar formation, including fibroblastic foci; interstitial inflammation typically mild to moderate and patchy
• bronchoalveolar lavage (BAL)
  
  • ​If a confident UIP pattern cannot be identified on high-resolution CT imaging, BAL for differential cell count may be a useful adjunct, as specific patterns such as an isolated elevation of lymphocytes (>40%) are unusual in IPF and suggest alternate diagnoses such as chronic hypersensitivity pneumonitis
• trans-bronchial biopsy
  
  • ​should not be routinely performed in the majority of patients
  • can be used to exclude differentials e.g. sarcoidosis
• C-reactive protein (CRP)
  
  • Although commonly observed in IPF, elevations in CRP are rarely practice-changing. Use of CRP in the management of IPF merits further investigation.
• erythrocyte sedimentation rate (ESR)
  
  • ​see above