Pulmonary capillaritis.

Pulmonary capillaritis is defined as a histopathologic pattern of alveolar wall inflammation that leads to the disruption of the integrity of alveolar-capillary basement membranes and flooding of the alveoli with blood. The clinical presentation is that of diffuse alveolar hemorrhage (DAH). Pulmonary capillaritis is usually the consequence of an underlying immune-mediated process that is systemic in nature. Rarely, pulmonary capillaritis occurs in isolation. This article outlines a systematic approach to the management of patients presenting with DAH, and provides an overview of specific causes of pulmonary capillaritis.