Necrotizing Pneumocystis carinii vasculitis associated with lung necrosis and cavitation in a patient with acquired immunodeficiency syndrome.

Pulmonary cavitation is an infrequent manifestation of Pneumocystis carinii pneumonia in patients with the acquired immunodeficiency syndrome. The pathogenesis of lung cavities associated with P carinii pneumonia has not been fully elucidated by detailed morphologic studies. This article describes a patient with the acquired immunodeficiency syndrome and P carinii pneumonia who developed roentgenographically identified lung cavitation while being treated with azidothymidine. At autopsy, necrotizing vasculitis with vascular infiltration by Pneumocystis organisms was associated with lung necrosis and cavitation. No other causes of pulmonary cavitation were identified. Thus, in patients with acquired immunodeficiency syndrome, P carinii, per se, may result in lung necrosis and cavitation, possibly through the mechanism of necrotizing angiitis.