Microscopic polyangiitis causing diffuse alveolar hemorrhage and rapidly progressive glomerulonephritis.

Diffuse alveolar hemorrhage complicating small vessel vasculitis is a life-threatening emergency and should be considered in the differential diagnosis of patients who develop rapidly progressive dyspnea with alveolar opacities on chest imaging. In these patients, the coexistence of pulmonary and renal involvement suggests a multisystem disease. We present a case of a man who presented to our hospital with diffuse alveolar hemorrhage, severe anemia, and rapidly progressive glomerulonephritis.