Patients with LAM usually develop progressive dyspnoea and recurrent pneumothorax, chylous collections and occasional haemoptysis 1. Extra pulmonary lymphadenopathy and cystic masses of the axial lymphatics termed lymphangioleiomyomas can result in abdominal and pelvic lymphatic obstruction 7. LAM is often associated with angiomyolipoma in the kidneys 8, and an increased frequency of meningioma 9. LAM varies in clinical features and rate of progression: this together with an absence of clear prognostic factors results in patients being given conflicting information about prognosis.

Patients with certain types of fibrosing interstitial lung disease (ILD) are at risk of developing a progressive phenotype characterised by self-sustaining fibrosis, decline in lung function, worsening quality of life, and early mortality. It has been proposed that such progressive fibrosing ILDs, which show commonalities in clinical behaviour and in the pathogenetic mechanisms that drive progressive fibrosis, may be “lumped” together for the purposes of clinical research and, potentially, for treatment. At present, no drugs are approved for the treatment of ILDs other than nintedanib and pirfenidone for the treatment of idiopathic pulmonary fibrosis. For other progressive fibrosing ILDs, the mainstay of drug therapy is immunosuppression. However, it is postulated that, once the response to lung injury in fibrosing ILDs has reached the stage at which fibrosis has become progressive and self-sustaining, targeted antifibrotic therapy would be required to slow disease progression. Nintedanib, an intracellular inhibitor of tyrosine kinases, has shown antifibrotic, anti-inflammatory and vascular remodelling effects in several non-clinical models of fibrosis, irrespective of the trigger for the injury. Ongoing clinical trials will provide insight into the role of antifibrotic treatment with nintedanib or pirfenidone in the management of fibrosing ILDs with a progressive phenotype.

Interstitial lung disease (ILD) encompasses a large and diverse group of pathological conditions that share similar clinical, radiological and pathological manifestations, despite potentially having quite different aetiologies and comorbidities. Idiopathic pulmonary fibrosis (IPF) represents probably the most aggressive form of ILD and systemic sclerosis is a multiorgan fibrotic disease frequently associated with ILD. Although the aetiology of these disorders remains unknown, in this review we analyse the pathogenic mechanisms by cell of interest (fibroblast, fibrocyte, myofibroblast, endothelial and alveolar epithelial cells and immune competent cells). New insights into the complex cellular contributions and interactions will be provided, comparing the role of cell subsets in the pathogenesis of IPF and systemic sclerosis.

The lung pathology of severe chronic obstructive pulmonary disease (COPD) has been poorly investigated. We examined surgical specimens obtained from patients with severe (forced expiratory volume in 1 second [FEV₁] = 29 ± 3% predicted, n = 9) or mild/no airflow limitation (FEV₁ = 86 ± 5% predicted, n = 9) and similar smoking history. With histochemical and immunohistochemical methods we quantified the structural changes and the inflammatory cells in small airways and in muscular pulmonary arteries. As compared with smokers with mild/no COPD, smokers with severe COPD had an increased number of leukocytes in the small airways, which showed a positive correlation with the radiologic score of emphysema and with the value of residual volume, and a negative correlation with the values of FEV₁ and carbon monoxide diffusing capacity. The inflammatory process was characterized by an increase in CD8⁺ and CD4⁺ T-lymphocytes in the airway wall and by an increase in macrophages in the airway epithelium. When all smokers were considered together, the smoking history was correlated with both the airway wall and smooth muscle thickness, suggesting that smoking itself may play a role in the development of structural changes. No structural and cellular differences were observed in pulmonary arteries between smokers with severe COPD and smokers with mild/no COPD. In conclusion, in the small airways of smokers with severe COPD, there is an increased number of leukocytes, which is correlated with reduced expiratory flow, lung hyperinflation, carbon monoxide diffusion impairment, and radiologic emphysema, suggesting a role for this inflammatory response in the clinical progression of the disease.

Pulmonary hypertension (PH) associated with chronic lung disease (CLD) is both common and underrecognised. The presence of PH in the setting of lung disease has been consistently shown to be associated with worse outcomes. Recent epidemiological studies have advanced understanding of the heterogeneity of this patient population and shown that defining both the specific type of CLD as well as the severity of PH ( i.e. deeper phenotyping) is necessary to inform natural history and prognosis. A systematic diagnostic approach to screening and confirmation of suspected PH in CLD is recommended. Numerous uncontrolled studies and one phase 3 randomised, controlled trial have suggested a benefit in treating PH in some patients with CLD, specifically those with fibrotic interstitial lung disease (ILD). However, other studies in diseases such as COPD-PH showed adverse outcomes with some therapies. Given the expanding list of approved pharmacological treatments for pulmonary arterial hypertension, developing a treatment algorithm for specific phenotypes of CLD-PH is required. This article will summarise existing data in COPD, ILD and other chronic lung diseases, and provide recommendations for classification of CLD-PH and approach to the diagnosis and management of these challenging patients.