Microscopic Polyangiitis with an Atypical Presentation

Abstract

Microscopic polyangiitis (MPA) is an antineutrophil cytoplasmic autoantibody‑associated vasculitis, usually affecting the small vessels in the form of systemic necrotizing vasculitis. It commonly manifests as diffuse alveolar hemorrhage and rapidly progressive glomerulonephritis but may present with the involvement of multiple organs. Timely diagnosis at an early localized stage is crucial for instituting an early disease‑specific treatment. We report a case of a 63-year-old female who was diagnosed with MPA predominantly involving lungs and middle ears. The absence of a typical pulmonary–renal presentation and clinical features favoring obstructive airway disease and tuberculosis led to a delayed diagnosis. The presence of antimyeloperoxidase antibodies in high titer and a clinical response to monoclonal antibody therapy, thereby confirming the diagnosis of MPA prompted us to report this case.