Interstital lung disease in ANCA vasculitis

Abstract

Anti-neutrophil cytoplasmic antibodies (ANCA) vasculitides are immune-mediated disorders that primarily affect small blood vessels of the airway and kidneys. Lung involvement, one of the hallmarks of microscopic polyangiitis and granulomatosis with polyangiitis, is associated with increased mortality and morbidity. In recent years, several retrospective series and case reports have described the association of interstitial lung disease (ILD) and ANCA vasculitis, particularly those positive for ANCA specific for myeloperoxidase. In the majority of these patients pulmonary fibrosis occurs concurrently or predates the diagnosis of ANCA vasculitis. More importantly, these studies have shown that ILD has an adverse impact on the long-term prognosis of ANCA vasculitis. This review focuses on the main clinical and radiologic features of pulmonary fibrosis associated with anti-neutrophil cytoplasmic antibodies. Major histopathology features, prognosis and therapeutic options are summarized.

Keywords: ANCA; Interstitial lung disease; Microscopic polyangiitis; Pulmonary fibrosis.

Fig. 1.

High-resolution computed tomography images of the two major patterns of interstitial pneumonia associated with ANCA. Representative features of usual interstitial pneumonia (UIP) are shown in A-D: honeycombing, cysts, and reticular opacities with basal and subpleural predominance. Nonspecific interstitial pneumonia (NSIP), characterized by patchy ground-glass opacities and traction bronchiectasis, is depicted in E-F. Courtesy of Dr. Lya Pensado.

Fig. 2.

Histopathology findings of interstitial lung disease associated ANCA. Usual interstitial pneumonia hallmarks are shown in A-C: marked variation in histologic appearance, fibroblast foci (A), patchy interstitial fibrosis (B), and honeycomb changes (C). Nonspecific interstitial pneumonia is characterized by diffuse alveolar wall thickening produced by fibrosis (D) and interstitial inflammation without fibrosis (E). Nonspecific interstitial pneumonia does not have significant fibroblastic foci or honeycombing (F). H&E stain. Courtesy of Dr. Rosa María Rivera-Rosales.