This patient presented with hemoptysis confirmed to be diffuse alveolar hemorrhage and chronic renal failure. The initial suspected etiology was volume overload due to missed dialysis sessions due to the elevated BNP level. The patient was treated conservatively with dialysis and while his reported hemoptysis improved, his chest x-ray showed persistent alveolar infiltrates. The serologic analysis that confirmed the diagnosis included Antinuclear Antibody of 1:360, P-ANCA positivity, and antibody to Myeloperoxidase of greater than 8.0 units. The constellation of diffuse alveolar hemorrhage, renal involvement, and p-ANCA/MPO positivity confirmed a diagnosis of Microscopic Polyangiitis. Imaging of the sinuses showed no signs of inflammation of the upper respiratory tract. The patient was treated with prednisone and cyclophosphamide pulse dosing for six doses. He had one subsequent episode of hemoptysis requiring hospitalization 1 month after initial presentation. In general, he responded well to treatment and was weaned from corticosteroids over the next 3 months after completion of cyclophosphamide with improvement on chest imaging (Fig. 34.4).