Rare Pulmonary Hemorrhage in Anti-Myeloperoxidase (MPO)-Associated Microscopic Polyangiitis: Case Report and Literature Review

Antineutrophil cytoplasmic antibodies (ANCA) is usually considered to be associated with autoimmune neutropenia, but the association between ANCA and autoimmune pulmonary hemorrhage has been rarely reported. In this case, we reported a 49 year-old woman with paroxysmal cough and hemoptysis. The symptom didn’t improve from any anti-infection treatment. Further autoantibodies analysis reveals ANCA positive (MPO-ANCA 1472.3 AAU/ml, normal <180.0 AAU/ml), and negative anti-GBM antibodies. The patient was diagnosed with microscopic polyangiitis, and was treated with methylprednisolone and cyclophosphamide. After 10 days treatment, the patient’s hemoptysis and paroxysmal cough was eliminated. CT scan also revealed a miniaturized pulmonary lesion. Although rare, ANCA-associated pulmonary lesion should be kept aware when other factors such as infection and toxin cannot explain the severe symptom. Early detection and routine autoantibodies analysis are needed to prevent condition from deteriorating further and minimize mortality.