• Clinical science

Interstitial lung disease


Interstitial lung diseases (ILDs) are a heterogeneous group of disorders marked by inflammatory changes in the alveoli. ILDs may be idiopathic or due to secondary causes such as autoimmune disease, pharmacotherapeutic changes, or exposure to toxic substances. These changes can cause irreversible fibrosis and impaired pulmonary function. The main symptoms are exertional dyspnea and a dry cough. Bibasilar inspiratory crackles or rales are usually heard on auscultation. Treatment is based on the underlying cause. Immune modulators and corticosteroids are used in cases of unknown etiology. In advanced stages of disease ILD can result in pulmonary insufficiency and respiratory heart failure with right ventricular insufficiency.


Occupational, environmental, and iatrogenic causes


Secondary to underlying disease

Idiopathic ILDs



Repeated cycles of tissue injury in the lung parenchyma with aberrant wound healing → collagenous fibrosis remodeling of the pulmonary interstitium [2]

Clinical features

  • Main symptoms
    • Exertional dyspnea that progresses to dyspnea at rest: Short shallow breaths may be taken by the patient to avoid dyspnea. [3]
    • Persistent nonproductive cough
    • Bibasilar, inspiratory crackles or rales on auscultation
    • Fatigue
  • Later stages of disease


Due to the wide variety of subtypes and symptoms, there is no generally recommended diagnostic algorithm. Physical examination, serology, pulmonary function tests, and imaging (chest X-ray, CT scan) is performed almost always, while lavage or biopsy depend on the individual case.


  • In secondary disease, the first step is to limit exposure to the toxic substance, cease therapy with the drug causing symptoms, or treat the underlying disease.
  • Antibiotics if bacterial interstitial pneumonia is suspected
  • Corticosteroids and immune modulators
  • Pirfenidone and nintedanib are commonly used for ILD.
  • Oxygen for symptomatic or end-stage ILD
  • Lung transplantation in end-stage ILD
  • The majority of patients with IPF (> 70%) do not respond to therapy and experience progressive respiratory failure.


  • 1. Meyer K, Decker C. Role of pirfenidone in the management of pulmonary fibrosis. Ther Clin Risk Manag. 2017; 13: pp. 427–437. doi: 10.2147/tcrm.s81141.
  • 2. Glasser SW, Hardie WD, Hagood JS. Pathogenesis of Interstitial Lung Disease in Children and Adults. Pediatric Allergy, Immunology, and Pulmonology. 2010; 23(1): pp. 9–14. doi: 10.1089/ped.2010.0004.
  • 3. Thomas Brack, Amal Jubran, Martin J. Tobin. Dyspnea and Decreased Variability of Breathing in Patients with Restrictive Lung Disease. Am J Respir Crit Care Med. 2002; 165(9): pp. 1260–1264. doi: 10.1164/rccm.2201018.
  • 4. Meyer KC, Raghu G. Bronchoalveolar lavage for the evaluation of interstitial lung disease: is it clinically useful?. The European respiratory journal. 2011; 38(4): pp. 761–9. doi: 10.1183/09031936.00069509.
  • 5. Margaritopoulos G, Vasarmidi E, Antoniou K. Pirfenidone in the treatment of idiopathic pulmonary fibrosis: an evidence-based review of its place in therapy. Core Evid. 2016; 11: pp. 11–22. doi: 10.2147/ce.s76549.
last updated 11/24/2020
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