Atypical presentation of Pneumocystis carinii pneumonia.

Pneumocystis carinii is a common cause of pneumonia in the immunosuppressed patient. Its radiological findings are usually homogeneous, diffuse and bilateral. We present a 27-year-old woman with non-Hodgkin's lymphoma presenting with unilateral right lung parenchymal infiltrates due to Pneumocystis carinii. In the immunosuppressed host, pneumonia limited to one lung should not preclude the diagnostic possibility of Pneumocystis carinii infection.