Prognostic value of radiological findings indeterminate for UIP pattern and anterior upper lobe honeycomb-like lesion in chronic fibrosing interstitial lung disease associated with MPO-ANCA

Pathogenesis of Pulmonary Manifestations in ANCA-Associated Vasculitis and Goodpasture Syndrome

Pulmonary manifestations of vasculitis are associated with significant morbidity and mortality in affected individuals. They result from a complex interplay between immune dysregulation, which leads to vascular inflammation and tissue damage. This review explored the underlying pathogenesis of pulmonary involvement in vasculitis, encompassing various forms such as granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA), and anti-GBM disease. Mechanisms involving ANCA and anti-GBM autoantibodies, neutrophil activation, and neutrophil extracellular trap (NETs) formation are discussed, along with the role of the complement system in inducing pulmonary injury. Furthermore, the impact of genetic predisposition and environmental factors on disease susceptibility and severity was considered, and the current treatment options were presented. Understanding the mechanisms involved in the pathogenesis of pulmonary vasculitis is crucial for developing targeted therapies and improving clinical outcomes in affected individuals.

Prediction model for respiratory-related mortality in microscopic polyangiitis with interstitial lung disease: multicentre REVEAL cohort study

OBJECTIVE

This study aimed to establish prediction models for respiratory-related mortality in microscopic polyangiitis (MPA) complicated by interstitial lung disease (ILD) using clinical characteristics.

METHODS

We enrolled patients with MPA with ILD between May 2005 and June 2021 in a multicentre cohort of Japanese patients with MPA (REVEAL cohort). We evaluated the demographic, clinical, laboratory, radiological findings, treatments and the presence of honeycombing 1 cm above the diaphragm using chest high-resolution CT (HRCT) on admission. We explored the risk factors predictive of respiratory-related mortality.

RESULTS

Of 115 patients, 26 cases died of respiratory-related diseases during a median follow-up of 3.8 years. Eighteen patients (69%) died due to respiratory infection, three (12%) had diffuse alveolar haemorrhage, and five (19%) had exacerbation of ILD. In univariate analysis, older age, lower percent forced vital capacity (%FVC), lower percent diffusing capacity of carbon monoxide (%DLCO), and the presence of honeycombing in the right lower lobe were identified as risk factors. Additionally, in multivariate analysis adjusted for age and treatment, %FVC, %DLCO and the presence of honeycombing in the right lower lobe were independently associated with respiratory-related mortality. We created prediction models based on the values of %FVC, %DLCO and presence of honeycombing on chest HRCT (termed "MPF model"). The 5-year respiratory-related death-free rate was significantly different between patients with MPA with ILD stratified by the number of risk factors based on the MPF model.

CONCLUSIONS

Our study indicates that the MPF model may help predict respiratory-related death in patients with MPA with ILD.

It Is Not Pneumocystis jiroveci (PCP), It Is Cyclophosphamide-Induced Pneumonitis

Cyclophosphamide (CYC) is an immunosuppressive medication used to treat life-threatening complications of various rheumatic diseases like vasculitis and systemic lupus erythematosus. A rare side effect of this medication is pneumonitis, which occurs in less than 1% of patients. We describe a case of an 83-year-old woman with a past medical history of microscopic polyangiitis, who presented with progressive dyspnea at rest, exacerbated on exertion, and associated with orthopnea that was attributed to CYC-induced pneumonitis. Three months before this presentation, the patient was diagnosed with antineutrophil cytoplasmic antibodies (ANCA)-positive pauci-immune crescentic and necrotizing glomerulonephritis and started on CYC. On admission, a computed tomography (CT) chest showed worsening bilateral ground-glass opacities in a mosaic distribution and inter and intralobular septal thickening, not present on the CT performed three months prior. The patient underwent an extensive workup, which included an echocardiogram, bronchoscopy with bronchoalveolar lavage, and viral respiratory panel to rule out infectious and cardiac pathologies. She was started on empiric treatment with antibiotics and diuretics, however, despite these interventions, she continued with respiratory distress. A multidisciplinary team convened, and the diagnosis of CYC-induced lung injury was entertained. The CYC was discontinued, and the patient was started on prednisone with significant improvement in symptoms. This case highlights the importance of recognizing CYC as a rare cause of interstitial pneumonitis. When considering CYC-induced lung toxicity, other etiologies, such as opportunistic infections, cardiac etiologies, and diffuse alveolar hemorrhage, should be ruled out.

Anti-Inflammatory and/or Anti-Fibrotic Treatment of MPO-ANCA-Positive Interstitial Lung Disease: A Short Review

The presence of a lung lesion is common in microscopic polyangiitis (MPA), and interstitial lung disease (ILD) can lead to a poor prognosis. Although myeloperoxidase antineutrophil cytoplasmic antibodies (MPO-ANCA) are often present in patients with MPA, patients with ILD and MPO-ANCA positivity but without other manifestations of systemic vasculitis have also been reported. Therefore, the possible association between MPO-ANCA, MPA, and idiopathic ILD remains unclear. This problematic matter has influenced the treatment strategy of MPO-ANCA-positive ILD patients without systemic vasculitis. Clinicians should undertake treatment with careful consideration of the four major causes of death in MPO-ANCA-positive ILD: acute exacerbation of ILD, progressive lung fibrosis, infectious comorbidities, and diffuse alveolar hemorrhage. Further, clinicians need to carefully judge whether inflammation or fibrosis is the dominant condition with reference to the patient’s clinical domain and radiopathological lung features. Recently, anti-fibrotic agents such as nintedanib and pirfenidone were shown to be effective in treating various etiologies associated with ILD and have thus led to the widening of treatment options. In this review, the clinical characteristics, radiopathology, prognosis, and therapeutic options in patients with MPO-ANCA-positive ILD are summarized using limited information from previous studies.