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External causes

HP

Hypersensitivity pneumonitis (HP) is caused by hypersensitivity to inhaled particles such as moulds, bird droppings (bird fancier’s lung) or chemicals.2,3

Highly specific to fibrotic HP is the ‘three-density-pattern’ i.e., a combination of ground glass opacities, lobules of decreased attenuation and vascularity and normal-appearing lung. In addition, air trapping may be apparent on the expiratory scan. The distribution of fibrosis may be mid lung zone-predominant, random both axially and craniocaudally, or relatively spared in the lower lung zones. Other distribution patterns may also be compatible with fHP, such as UIP.15

External causes

A comprehensive case history focused on exposure to potential triggers such as feathers, birds and moulds, together with a substantially raised number of lymphocytes on bronchoalveolar lavage and/or IgG antibodies for a specific antigen (e.g. pigeon, aspergillus) is recommended to identify fibrotic HP.2,15,16

Drug-induced ILD

Certain drugs can cause pulmonary fibrosis: amiodarone which is used to treat arrhythmias, for example, most chemotherapies (e.g. bleomycin), even if targeted, or nitrofurantoin, an antibiotic used for urinary tract infections.17

Radiation-induced lung injury can sometimes also lead to permanent damage in the form of pulmonary fibrosis. The same applies to tobacco smoke.17

Other exposure related ILDs

Pneumoconiosis is caused by the inhalation and retention of harmful particles in the lungs. This exposure is usually occupational (for example asbestosis and silicosis). Exposure to agricultural environments/cattle, metal, coal, and chemicals that are released during the production of dental prosthetics can also be associated with ILD/fibrosis.2,3

References:

  1. Wijsenbeek M, Cottin V. Spectrum of Fibrotic Lung Diseases. N Engl J Med. 2020;383(10):958-68.

  2. Cottin V, Hirani NA, Hotchkin DL, et al. Presentation, diagnosis and clinical course of the spectrum of progressive-fibrosing interstitial lung diseases. Eur Respir Rev. 2018;27(150).

  3. Olson AL, Gifford AH, Inase N, et al. The epidemiology of idiopathic pulmonary fibrosis and interstitial lung diseases at risk of a progressive-fibrosing phenotype. Eur Respir Rev. 2018;27(150):180077.

  4. Fischer A, Strek ME, Cottin V, et al. Proceedings of the American College of Rheumatology/Association of Physicians of Great Britain and Ireland Connective Tissue Disease-Associated Interstitial Lung Disease Summit: A Multidisciplinary Approach to Address Challenges and Opportunities. Arthritis Rheumatol. 2019;71(2):182-95.

  5. Vij R, Strek ME. Diagnosis and treatment of connective tissue disease-associated interstitial lung disease. Chest. 2013;143(3):814-24.

  6. Mira-Avendano I, Abril A, Burger CD, et al. Interstitial Lung Disease and Other Pulmonary Manifestations in Connective Tissue Diseases. Mayo Clin Proc. 2019;94(2):309-25.

  7. Kim EJ, Elicker BM, Maldonado F, et al. Usual interstitial pneumonia in rheumatoid arthritis associated interstitial lung disease. Eur Respir J. 2010;35(6):1322-8.

  8. Denton CP, Khanna D. Systemic sclerosis. The Lancet. 2017;390(10103):1685-99.

  9. Nihtyanova SI, Schreiber BE, Ong VH, et al. Prediction of pulmonary complications and long term survival in systemic sclerosis. Arthritis & rheumatology. 2014;66(6):1625-35.

  10. Grunewald J, Grutters JC, Arkema EV, et al. Sarcoidosis. Nat Rev Dis Primers. 2019;5(1):45.

  11. Arkema EV, Cozier YC. Sarcoidosis epidemiology: recent estimates of incidence, prevalence and risk factors. Curr Opin Pulm Med. 2020;26(5):527-34.

  12. ATS Board of Directors, Committee EE. Statement on sarcoidosis. Joint Statement of the American Thoracic Society (ATS), the European Respiratory Society (ERS) and the World Association of Sarcoidosis and Other Granulomatous Disorders (WASOG) adopted by the ATS Board of Directors and by the ERS Executive Committee, February 1999. Am J Respir Crit Care Med. 1999;160(2):736-55.

  13. Ungprasert P, Ryu JH, Matteson EL. Clinical Manifestations, Diagnosis, and Treatment of Sarcoidosis. Mayo Clin Proc Innov Qual Outcomes. 2019;3(3):358-75.

  14. Patterson KC, Strek ME. Pulmonary fibrosis in sarcoidosis. Clinical features and outcomes. Ann Am Thorac Soc. 2013;10(4):362-70.

  15. Raghu G, Remy-Jardin M, Ryerson CJ, et al. Diagnosis of Hypersensitivity Pneumonitis in Adults. An Official ATS/JRS/ALAT Clinical Practice Guideline. Am J Respir Crit Care Med. 2020;202(3):e36-e69.

  16. Spagnolo P, Rossi G, Cavazza A, et al. Hypersensitivity Pneumonitis: A Comprehensive Review. J Investig Allergol Clin Immunol. 2015;25(4):237-50; quiz follow 50.

  17. Spagnolo P, Bonniaud P, Rossi G, et al. Drug-induced interstitial lung disease. Eur Respir J. 2022.