Trusted medical expertise in seconds.

Access 1,000+ clinical and preclinical articles. Find answers fast with the high-powered search feature and clinical tools.

Try free for 5 days
Evidence-based content, created and peer-reviewed by physicians. Read the disclaimer.

Interstitial lung disease

Last updated: June 8, 2021

Summarytoggle arrow icon

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]

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.

Differential diagnoses of pneumoconioses [6]
Type Etiology Population at risk Clinical features Chest x-ray
  • Asbestos miners and millers
  • Workers of brake linings, insulations manufactures
  • Ship construction workers
  • Demolishers
  • Firefighters
  • Plumbers
  • Roofers
  • Crystalline silica dust
  • Miners
  • Workers of quarries, ceramics production, glass manufacturers
  • Construction workers
  • Eggshell calcifications
  • Bilateral diffuse ground-glass opacities
  • Large number of rounded, solitary, small (< 1 cm) opacities particularly in the upper lobe of the lungs
Aluminosis [7][8]
  • Aluminum dust
  • Welders (e.g., automobile industry)
  • Nodular or diffuse infiltrates (predominantly affects the upper lung fields)
  • Small cystic radiolucencies (“honeycombing”) [8]
Anthracosis [9][10]
  • Carbon dust and sooty air
  • City dwellers
  • Coal miners
  • More mild than other types of pneumoconiosis, usually asymptomatic
  • Pulmonary fibrosis rarely occurs.
  • Upper lobes of the lungs are primarily affected.
  • Heterogenous pulmonary infiltrates, with/without mass lesion
Coal workers' pneumoconiosis [9][10]
  • Fine nodular opacifications (< 1 cm) in upper lung zone
  • Beryllium
  • Workers in manufacturing industries where alloys are frequently used (often high-tech)
    • Aerospace engineering
    • Nuclear and electronics plants
    • Ceramics industries
    • Dental material production
    • Dye manufacturing
Pulmonary siderosis [13][14]
  • Welders, iron miners, foundry workers
  • Usually asymptomatic; occasionally, presents with features similar to COPD
  • Pulmonary fibrosis rarely occurs.
  • Small, round, patchy shadows on x-ray

Although coal is mined from under the earth, the upper lobes of the lungs are primarily affected.

  • 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 : p.427-437. doi: 10.2147/tcrm.s81141 . | Open in Read by QxMD
  2. Glasser SW, Hardie WD, Hagood JS. Pathogenesis of Interstitial Lung Disease in Children and Adults. Pediatric Allergy, Immunology, and Pulmonology. 2010; 23 (1): p.9-14. doi: 10.1089/ped.2010.0004 . | Open in Read by QxMD
  3. Nemery B. Metal toxicity and the respiratory tract. Eur Respir J. 1990; 3 (2): p.202-219.
  4. Karkhanis VS, Joshi JM. Pneumoconioses. Indian J Chest Dis Allied Sci. 2013; 55 (1): p.25-34.
  5. Smolkova P, Nakladalova M. The etiology of occupational pulmonary aluminosis - the past and the present. Biomedical Papers. 2014; 158 (4): p.535-538. doi: 10.5507/bp.2014.017 . | Open in Read by QxMD
  6. Smolková P, Nakládalová M, Tichý T, Hampalová M, Kolek V. Occupational pulmonary aluminosis: a case report. Ind Health. 2014; 52 (2): p.147-151. doi: 10.2486/indhealth.2012-0154 . | Open in Read by QxMD
  7. Leonard R, Zulfikar R, Stansbury R. Coal mining and lung disease in the 21st century. Curr Opin Pulm Med. 2020; 26 (2): p.135-141. doi: 10.1097/mcp.0000000000000653 . | Open in Read by QxMD
  8. Mirsadraee M. Anthracosis of the lungs: etiology, clinical manifestations and diagnosis: a review. Tanaffos. 2014; 13 (4): p.1-13.
  9. Dweik RA. Berylliosis Medication. In: Mosenifar Z, Berylliosis Medication. New York, NY: WebMD. Updated: December 31, 2015. Accessed: April 22, 2020.
  10. Boffetta P, Fordyce TA, Mandel JS. A mortality study of beryllium workers. Cancer Medicine. 2016; 5 (12): p.3596-3605. doi: 10.1002/cam4.918 . | Open in Read by QxMD
  11. Khalid I, Khalid TJ, Jennings JH. A welder with pneumosiderosis: a case report. Cases Journal. 2009; 2 (1): p.6639. doi: 10.1186/1757-1626-2-6639 . | Open in Read by QxMD
  12. Akar E, Yildiz T, Atahan S. Pulmonary siderosis cases diagnosed with minimally invasive surgical technique: A retrospective analysis of 7 cases. Annals of Thoracic Medicine. 2018; 13 (3): p.163. doi: 10.4103/atm.atm_152_17 . | Open in Read by QxMD
  13. 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): p.1260-1264. doi: 10.1164/rccm.2201018 . | Open in Read by QxMD
  14. Meyer KC, Raghu G. Bronchoalveolar lavage for the evaluation of interstitial lung disease: is it clinically useful?. The European respiratory journal. 2011; 38 (4): p.761-9. doi: 10.1183/09031936.00069509 . | Open in Read by QxMD
  15. 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 : p.11-22. doi: 10.2147/ce.s76549 . | Open in Read by QxMD