Mediastinal lymph node enlargement in idiopathic pulmonary fibrosis: relationships with disease progression and pulmonary function trends

Lung Cancer and Interstitial Lung Diseases

Lung cancer continues to be one of the leading causes of cancer-related death worldwide. There is evidence of a complex interplay between lung cancer and interstitial lung disease (ILD), affecting disease progression, management strategies, and patient outcomes. Both conditions develop as the result of common risk factors such as smoking, environmental exposures, and genetic predispositions. The presence of ILD poses diagnostic and therapeutic challenges in lung cancer management, including difficulties in interpreting radiological findings and increased susceptibility to treatment-related toxicities, such as acute exacerbation of ILD after surgery and pneumonitis after radiation therapy and immunotherapy. Moreover, due to the lack of large, phase III randomized controlled trials, the evidence-based therapeutic options for patients with ILDs and lung cancer remain limited. Antifibrotic treatment may help prevent pulmonary toxicity due to lung cancer treatment, but its effect is still unclear. Emerging diagnostic modalities and biomarkers and optimizing personalized treatment strategies are essential to improve outcomes in this patient population.

Association between Parenchymal B-Cell Follicles and CT-Proven Enlarged Mediastinal Lymph Nodes in Patients with Pulmonary Fibrosis

BACKGROUND

Mediastinal lymph node enlargement (MLNE) is a finding described in a subset of patients with idiopathic pulmonary fibrosis (IPF) and other interstitial lung diseases (ILDs) and is associated with accelerated disease progression and increased mortality. The cause of MLNE is still not known. Our hypothesis is that there is an association between MLNE and B-cell follicles in lung tissue, another aspect detectable in the lung tissue of patients with IPF and other ILDs.

OBJECTIVES

The aim of this study was to assess if there is an association between MLNE and B-cell follicles in lung tissue in patients with IPF and other ILDs.

METHOD

Patients having transbronchial cryobiopsies performed as part of an investigation for ILD were included in this prospective observational study. MLNE (smallest diameter ≥10 mm) were assessed in station 7, 4R, and 4L on high-resolution computed tomography scans. B-cell follicles were assessed on haematoxylin-eosin-stained specimens. Lung function, 6-minute walk test, acute exacerbation, and mortality were registered after 2 years. In addition, we investigated if the finding of B-cell follicles was consistent in patients who underwent both surgical lung biopsies (SLBs) and cryobiopsies.

RESULTS

In total, 93 patients were included for analysis (46% diagnosed with IPF, 54% diagnosed with other ILDs). MLNE was found in 26 (60%) of the IPF patients and in 23 (46%) of the non-IPF patients (p = 0.164). Diffusing capacity for carbon monoxide was significantly lower (p = 0.03) in patients with MLNE compared to patients without MLNE. B-cell follicles were found in 11 (26%) of the IPF patients and in 22 (44%) of the non-IPF patients (p = 0.064). Germinal centres were not seen in any of the patients. There was no association between MLNE and B-cell follicles (p = 0.057). No significant difference in change of pulmonary function test was seen at 2-year follow-up when comparing the patients with and without MLNE or B-cell follicles. In 13 patients, both SLBs and cryobiopsies were performed. The presence of B-cell follicles was not consistent when comparing the two different methods.

CONCLUSION

MLNE is evident in a substantial part of patients with ILD and is associated with lower DLCO at inclusion. We could not demonstrate an association between histological B-cell follicles in biopsies and MLNE. A possible explanation for this is that the cryobiopsies might not have captured the changes we sought.

The Vasculature in Pulmonary Fibrosis

Purpose of Review

The current paradigm of idiopathic pulmonary fibrosis (IPF) pathogenesis involves recurrent injury to a sensitive alveolar epithelium followed by impaired repair responses marked by fibroblast activation and deposition of extracellular matrix. Multiple cell types are involved in this response with potential roles suggested by advances in single-cell RNA sequencing and lung developmental biology. Notably, recent work has better characterized the cell types present in the pulmonary endothelium and identified vascular changes in patients with IPF.

Recent Findings

Lung tissue from patients with IPF has been examined at single-cell resolution, revealing reductions in lung capillary cells and expansion of a population of vascular cells expressing markers associated with bronchial endothelium. In addition, pre-clinical models have demonstrated a fundamental role for aging and vascular permeability in the development of pulmonary fibrosis.

Summary

Mounting evidence suggests that the endothelium undergoes changes in the context of fibrosis, and these changes may contribute to the development and/or progression of pulmonary fibrosis. Additional studies will be needed to further define the functional role of these vascular changes.

Usefulness of Body Composition CT Analysis in Patients with Idiopathic Pulmonary Fibrosis: A Pilot Study

PURPOSE

To evaluate the feasibility of a chest CT-based body composition analysis in idiopathic pulmonary fibrosis (IPF), and to investigate the respective contribution of lung and muscle CT quantitative analyses to the prognosis of IPF.

METHOD

A total of 71 IPF patients were recruited at diagnosis. All patients underwent a standard chest CT-scan and a bioelectrical impedance analysis considered as reference standard for estimating malnutrition through the use of the fat-free mass index (FFMI). The skeletal muscle index (SMI) was measured on chest-CT at the level of the first lumbar vertebra by two radiologists. Lung fibrosis extent was quantified by three radiologists in consensus. The extent of emphysema, the pulmonary artery to aorta (PA/AO) diameter ratio and lymph node enlargement were also reported. Mortality and hospitalization over a 14-month follow-up were recorded.

RESULTS

A low FFMI defining malnutrition was identified in 26.8% of patients. SMI was significantly lower in these patients (p<0.001) and was correlated with FFMI (r=0.637, p<0.001). Interobserver agreement of SMI measurement was very good (ICC=0.91). For diagnosing malnutrition, SMI showed a 0.79 sensitivity, a 0.69 specificity, a 0.48 PPV and a 0.90 NPV. In univariate analysis, fibrosis extent was significantly associated with death, while SMI did not reach significance. In multivariate analysis, fibrosis extent and PA/AO ratio were independently associated with hospitalization.

CONCLUSIONS

SMI measured on chest CT could be a reliable tool to exclude malnutrition in IPF. A quantitative analysis of both fibrosis and skeletal muscle may allow holistic management of IPF patients.