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Pulmonary involvement in ANCA-associated vasculitis from the view of the pulmonologist

Sakae Homma1, Aika Suzuki2, Keita Sato2

  • 1Department of Respiratory Medicine, Toho University Omori Medical Center, Tokyo, 143-8541, Japan. sahomma@med.toho-u.ac.jp.

Clinical and Experimental Nephrology
|November 29, 2012
PubMed

Insights

Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV) can manifest as pulmonary fibrosis (PF), often mimicking idiopathic pulmonary fibrosis (IPF). Early recognition of microscopic polyangiitis (MPA) in PF patients is crucial for accurate diagnosis and treatment.

Area of Science:

  • Rheumatology and Pulmonology
  • Immunology and Autoimmune Diseases
  • Radiology and Pathology

Background:

  • Antineutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis (AAV), encompassing microscopic polyangiitis (MPA), granulomatosis with polyangiitis (GPA), and eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome), frequently involves the lungs.
  • Pulmonary fibrosis (PF) is a common and significant manifestation in AAV, particularly in MPA, where diffuse alveolar hemorrhage and fibrotic changes are prevalent.
  • High-resolution computed tomography (HRCT) and histological findings in MPA-associated PF, such as usual interstitial pneumonia (UIP) and fibrotic nonspecific interstitial pneumonia (F-NSIP), can resemble idiopathic pulmonary fibrosis (IPF).

Purpose of the Study:

  • To highlight the importance of recognizing MPA as an underlying cause of pulmonary fibrosis (PF).
  • To differentiate PF in MPA from idiopathic pulmonary fibrosis (IPF) based on distinct radiological and pathological features.
  • To inform clinicians about the clinical presentations and management strategies for various ANCA-associated vasculitis (AAV) conditions affecting the lungs.

Main Methods:

  • Review of high-resolution computed tomography (HRCT) chest findings in MPA patients with pulmonary fibrosis (PF).
  • Analysis of histological patterns of PF in MPA, comparing them with idiopathic pulmonary fibrosis (IPF).
  • Examination of clinical features and treatment protocols for MPA, GPA, and Churg-Strauss syndrome, including a severity-based regimen for Japanese patients with myeloperoxidase (MPO)-ANCA-associated vasculitis (JMAAV).

Main Results:

  • MPA in PF patients frequently shows UIP, F-NSIP, or combined PF and emphysema (CPFE) patterns on HRCT, with characteristic features like honeycombing and ground-glass opacity.
  • Histological examination reveals extensive interstitial fibrosis, lymphoid hyperplasia, and bronchiolitis in MPA-associated PF, distinguishing it from IPF.
  • Pulmonary limited MPA can occur, and PF may precede MPA diagnosis; survival in UIP pattern/MPA is comparable to IPF.

Conclusions:

  • Clinicians must consider MPA in patients presenting with pulmonary fibrosis (PF) to avoid misdiagnosis as idiopathic pulmonary fibrosis (IPF).
  • Distinct radiological and histological findings aid in differentiating MPA-associated PF from IPF.
  • Understanding the varied pulmonary manifestations of AAV is essential for appropriate patient management and treatment.

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