[Pulmonary manifestations of ANCA-associated vasculitis in imaging]

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) such as granulomatosis with polyangiitis (GPA), eosinophilic granulomatosis with polyangiitis (EGPA), and microscopic polyangiitis (MPA) are rare autoimmune diseases that frequently involve the lungs and may present with life-threatening complications. Their differentiation can be challenging due to overlapping clinical and radiological findings.

High-resolution computed tomography (HRCT) is the key imaging modality for detecting pulmonary changes such as nodules, ground-glass opacities, and consolidations. Chest X‑ray and contrast-enhanced computed tomography (CT) are also used.

Newer techniques such as low-dose CT, perfusion CT, and structured serial imaging offer improved detection of diffuse alveolar hemorrhage (DAH), granulomatous inflammation, and airway involvement.

HRCT achieves sensitivities up to 90% in pulmonary AAV manifestations like DAH. Specificity remains limited, requiring integration of clinical and serological findings. Advanced methods enhance lesion characterization and assessment of disease activity.

Radiology enables early identification of distinct pulmonary patterns (e.g., cavitary nodules in GPA, peripheral migratory consolidations in EGPA, perihilar DAH in MPA). Although not pathognomonic, imaging is highly valuable when interpreted in context.

Diagnostic work-up is best conducted in interdisciplinary centers. HRCT should be performed in suspected pulmonary AAV. Contrast-enhanced CT is useful in suspected hemorrhage or necrosis. Radiological interpretation must be combined with clinical data, ANCA serology, and potentially histology.