Pneumonia due to Pneumocystis carinii in a transplant recipient with normal arterial oxygen tension and normal radiographic findings.

We have described an exogenously immunosuppressed, HIV-negative patient with a subacute presentation of Pneumocystis carinii pneumonia characterized by normal arterial oxygen tension and alveolar-arterial oxygen gradient and normal findings on serial chest radiographs. This case demonstrates that other studies in addition to chest radiograph and resting arterial blood gas measurement are necessary in all immunosuppressed patients with progressive respiratory symptoms, regardless of cause of immunosuppression, to exclude P carinii pneumonia from the differential diagnosis.