Interstitial Lung Disease with ANCA-associated Vasculitis

Area of Science:

• Rheumatology
• Pulmonology
• Immunology

Background:

• The link between interstitial lung disease (ILD) and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) has been increasingly recognized.
• Pulmonary fibrosis is a common manifestation in AAV patients, sometimes preceding systemic vasculitis symptoms.
• Myeloperoxidase (MPO)-ANCA and microscopic polyangiitis (MPA) are predominant in AAV-ILD cases.

Purpose of the Study:

• To summarize the current understanding of the association between ILD and AAV.
• To highlight the clinical presentation, pathological findings, and prognostic implications of ILD in AAV.
• To discuss the phenomenon of ANCA-positive conversion in idiopathic pulmonary fibrosis.

Main Methods:

• Review of case reports and case series published over the last two decades.
• Analysis of clinical, radiological, and pathological findings in AAV patients with ILD.
• Examination of ANCA seroconversion in patients with idiopathic pulmonary fibrosis.

Main Results:

• A significant association exists between ILD and AAV, particularly MPA.
• Pulmonary fibrosis is often the initial clinical manifestation in AAV patients.
• Usual interstitial pneumonia (UIP) pattern is common in AAV-ILD lungs.
• AAV patients with ILD generally have a poorer prognosis compared to those without ILD.

Conclusions:

• ILD is a significant comorbidity in AAV, frequently presenting as pulmonary fibrosis.
• MPO-ANCA and MPA are strongly associated with the AAV-ILD subset.
• The presence of ILD portends a worse prognosis for patients with AAV.