MPO-ANCA positive interstitial pneumonia: Current knowledge and future perspectives

Area of Science:

• Pulmonary Medicine
• Rheumatology
• Immunology

Background:

• Interstitial pneumonia is a significant respiratory complication in microscopic polyangiitis (MPA).
• The precise pathogenesis of interstitial pneumonia during MPA's clinical course remains understudied.
• Myeloperoxidase (MPO)-antineutrophil cytoplasmic antibody (ANCA) positive interstitial pneumonia is increasingly recognized as a potential precursor to MPA.

Purpose of the Study:

• To review the clinical questions surrounding MPO-ANCA positive interstitial pneumonia.
• To summarize current evidence regarding the relationship between MPO-ANCA positive interstitial pneumonia and ANCA-associated vasculitis (AAV).
• To identify gaps in knowledge and future research directions.

Main Methods:

• Literature review of existing studies on MPA, interstitial pneumonia, and ANCA.
• Analysis of clinical data and diagnostic criteria related to MPO-ANCA positive interstitial pneumonia.
• Discussion of expert opinions and consensus among pulmonologists and rheumatologists.

Main Results:

• Interstitial pneumonia is a key feature in MPA, but its specific development pathway within MPA is not well understood.
• A subset of patients with MPO-ANCA positive interstitial pneumonia may develop MPA, though the incidence and diagnostic criteria are debated.
• There is ongoing debate regarding the classification of MPO-ANCA positive interstitial pneumonia without other organ involvement as a form of AAV.

Conclusions:

• Further research is needed to elucidate the pathogenesis of interstitial pneumonia in MPA.
• Establishing clear diagnostic criteria for MPO-ANCA positive interstitial pneumonia is crucial for accurate classification and management.
• Collaboration between pulmonologists and rheumatologists is essential to address the diagnostic and classification challenges of MPO-ANCA positive interstitial pneumonia in the context of AAV.