Antineutrophil Cytoplasmic Antibody (ANCA)-Associated Vasculitic Orbital Syndromes

Orbital inflammation is the most common orbital clinical condition encountered by the ophthalmologist. While infections are most common in children and young adults, noninfectious inflammations are commonly encountered in all age groups. Although “pseudotumor” of the orbit was considered the most common noninfectious orbital inflammatory condition, a complete laboratory workup, appropriate imaging, and more importantly histopathological examination with immunohistochemical techniques have narrowed the diagnosis to one of many specific orbital inflammatory conditions. Among the various types, vasculitic etiology is becoming increasingly recognized more commonly, and various forms of systemic and both extensive and limited forms of antineutrophil cytoplasmic antibody (ANCA)-associated inflammations are being increasingly recognized. Eponymous names have given way to disease-descriptive diagnostic names which are now being widely adopted as endorsed by international societies dealing with immunologic disorders. Specific entities like giant cell arteritis, polyarteritis nodosa, granulomatosis with polyangiitis, and allergic granulomatosis with polyangiitis are highlighted. The current chapter provides an overview of ANCA-associated vasculitis-related orbital inflammation with a conceptual approach to their diagnosis and management.