Microscopic polyangiitis (MPA) is a rare systemic vasculitis, antineutrophil cytoplasmic antibody associated, characterized by necrotizing small vessel involvement with few or no immune complex deposits. Necrotizing glomerulonephritis is common. Pulmonary capillaritis causing alveolar hemorrhage and hemoptysis is well recognized, but most case series are reported in the nephrology literature and emphasize renal considerations. We present a single-center 10-year retrospective review of 40 patients meeting the 2012 Revised Chapel Hill Nomenclature of MPA, with specific p-antineutrophil cytoplasmic antibody and myeloperoxidase positivity, emphasizing initial and subsequent pulmonary manifestations.
We searched the electronic database of our large integrated clinic-hospital system and reviewed charts of all patients with related International Classification of Diseases, Ninth Revision codes for vasculitis in the last 10 years. Several variables were reviewed.
Onset of illness was usually abrupt and included respiratory symptoms, and the most common presenting complaint was cough. Hemoptysis occurred during the course of illness in 40%. Pulmonary complaints were found in 80% of patients upon presentation, whereas pulmonary infiltrates were noted in 92%. Managing subspecialty and treatment modalities were quite variable.
Pulmonary involvement is much more frequent than the currently reported 25% to 50% when features in addition to hemorrhage are recorded. No clear guidelines direct the evaluation and management of MPA patients. Consistent communication between pulmonary, nephrology, and rheumatology services could improve our understanding of the disease process.