11th January 2024

Complications

Many ILD complications are common to all subtypes, while others are specific to certain conditions.

Lung cancer

• ILD is an independent risk factor for developing lung malignancy, which could be partially secondary to increased cell damage due to inflammatory nature of the condition. An estimated 15-20% of ILD patients develop lung cancer.
• It is often challenging to diagnose, as emerging symptoms are often contributed to the already-known diagnosis of ILD. Constitutional symptoms such as new weight and appetite loss, new haematemesis or chest pain should prompt further investigations with imaging +/- bronchoscopy.
• Mesothelioma is a rare but highly aggressive type of lung cancer. Up to 90% of all cases are linked to asbestos exposure. Note that asbestos exposure also increases the risk of other types of cancer.
• Perhaps not surprisingly, lung malignancy is associated with higher morbidity and mortality in patients with ILD compared to patients without ILD.

Infections

• Chest infections are commoner in patients with ILD. They are important to avoid, and if they do occur, they should be treated swiftly as they are linked to ILD progression.
• All infections are more common in ILD (bacterial, viral, fungal); incidence of tuberculosis, in particular, was shown to be up to 4-5 times higher than in patients without ILD.
• Impaired defence mechanisms due to lung injury and scarring, as well as immunosuppressive medications with which ILD is often treated, both predispose this cohort of patients to chest infections.
• Fibrotic conditions such as IPF are not treated with immunosuppression; thus, patients with exacerbation should always be covered with broad-spectrum antibiotics for a potential infective cause.
• In non-IPF ILD, however, acute deterioration might present a clinical dilemma. It is important to distinguish between non-infective and infective exacerbation, as it might call for either increase in immunosuppression or reduction of it in combination with antibiotic treatment. BAL and/or sputum culture are key investigations to make this distinction in unclear cases.

Pulmonary arterial hypertension

• This is a frequent late-stage complication of many ILDs, in particular IPF, sarcoidosis and CTD-ILD.
• As fibrosis progresses, affected parts of the lung become hypoxic. This leads to reactive vasoconstriction and redistribution of the blood to better-ventilated parts of the lung. These processes, in turn, lead to rise in intravascular pressure, wall stress and further release of inflammatory and proliferative cytokines. It also puts stress on the right heart, which has to pump against the high pressures, eventually leading to right heart failure.
• ILD-related PAH is associated with reduced exercise capacity, poorer quality of life, and shorter life span.
• It can be difficult to diagnose, as symptoms are similar to those of ILD. It should be suspected in any patient showing significant clinical deterioration, especially when it seems to be out of proportion to their lung function tests, and in any patient showing signs/symptoms of heart failure.
• Echocardiogram is usually the first investigation as it is a great non-invasive test to screen for the condition. Right heart catheterisation (RHC) remains the gold standard; mean pulmonary artery pressure more than 20 mm Hg is diagnostic.
• Treatment options include supportive management, including supplemental oxygen, and heart failure therapy. There are currently no medical therapies approved for ILD-PAH (note that this is different from the primary pulmonary hypertension, which has multiple treatment options).

Pneumothorax

• Pneumothorax occurs more commonly in patients with respiratory diseases, and up to 20% of ILD patients develop this complication at some point.
• All ILD patients with pneumothorax should be admitted for at least 24 hours.
• Pneumothorax size should be measured using distance between hilum and ribcage. This will determine further steps:
  1. If the patient is breathless at presentation, or their pneumothorax is >2cm, chest drain should be inserted
  2. If the patient is not breathless, and their pneumothorax is 1-2cm, aspirate up to 2.5L of air with a cannula and assess response with a chest x-ray. If pneumothorax is still >1cm, chest drain should be inserted. If it reduces to <1cm, admit for 24hrs with high-flow oxygen
  3. If the patient is not breathless, and their pneumothorax is <1cm, admit for 24hrs with high-flow oxygen
• Such patients should always be discussed with a chest physician on admission, and if air leak persists at 48hrs after drain insertion – with thoracic surgeons for consideration of surgical management.

Caplan syndrome

• Rare complication of pneumoconiosis (in particular, coal worker’s lung and silicosis), which occurs in patients with rheumatoid arthritis (RA)
• In this condition, rheumatoid nodules develop on the periphery of lungs, with the background of pnemoconiotic changes.
• These nodules can develop rapidly within weeks. In this case, they can either lead to acute worsening of the known ILD or manifest as its first presentation.

References

• Brown SW, Dobelle M, Padilla M, Agovino M, Wisnivesky JP, Hashim D, Boffetta P. Idiopathic Pulmonary Fibrosis and Lung Cancer. A Systematic Review and Meta-analysis. Ann Am Thorac Soc. 2019 Aug;16(8):1041-1051. doi: 10.1513/AnnalsATS.201807-481OC. PMID: 30892054.
• Naccache JM, Gibiot Q, Monnet I, Antoine M, Wislez M, Chouaid C, Cadranel J. Lung cancer and interstitial lung disease: a literature review. J Thorac Dis. 2018 Jun;10(6):3829-3844. doi: 10.21037/jtd.2018.05.75. PMID: 30069384; PMCID: PMC6051867.
• George A. Margaritopoulos, Katerina M. Antoniou, Athol U. Wells. Comorbidities in interstitial lung diseases. European Respiratory Review March 2017, 26 (143) 160027; DOI: 10.1183/16000617.0027-2016
• Watanabe T, Tanahashi M, Suzuki E, Yoshii N, Tsuchida H, Yobita S, Iguchi K, Uchiyama S, Nakamura M. Treatment of secondary pneumothorax with interstitial lung disease: the surgical indications at the start of treatment is important. J Thorac Dis. 2022 May;14(5):1393-1400. doi: 10.21037/jtd-21-1851. PMID: 35693624; PMCID: PMC9186251.
• MacDuff A, Arnold A, Harvey J. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010. Thorax 2010;65:ii18-ii31.
• Stark P. Imaging of occupational lung diseases. Ed. Dieffenbach P. UptoDate.com, update 08/11/22, accessed on 01/01/2023.