Hypoxemia with normal chest roentgenogram due to Pneumocystis carinii pneumonia. Diagnostic errors due to low suspicion of AIDS.

Three patients encountered in a single month had insidious development of atypical respiratory or systemic symptoms and were found to be hypoxemic. All had normal chest roentgenograms and were perplexing problems in diagnosis. On initial presentation, none had evidence of pulmonary infection or recognized clinical or social features that suggested acquired immunodeficiency syndrome (AIDS). All received corticosteroids for respiratory distress before the correct diagnosis was made, and all died rapidly of Pneumocystis pneumonia secondary to AIDS.