Legionella lung cavitation.

Pneumonia due to Legionella has been identified in a small percentage of patients suffering from acquired immune deficiency syndrome (AIDS), with and without coexisting Pneumocystis carinii pneumonia. On chest radiographs Legionella typically produces focal parenchymal opacities and confluent lobar consolidation. The authors describe a case of cavitating Legionella pneumonia, which occurred in a 38-year-old man who had AIDS. The main differential diagnoses are an unusual presentation of P. carinii pneumonia and fungal infection. The authors also emphasize the increasing recognition of bacterial pneumonia with atypical radiologic features in AIDS patients.