Radiological features of Pneumocystis jirovecii Pneumonia in immunocompromised patients with and without AIDS.

The aim of this study was to compare chest computerized tomography (CT) findings of Pneumocystis jirovecii pneumonia (PCP) in immunocompromised patients with and without acquired immune deficiency syndrome (AIDS). Chest CT findings and clinical parameters of 38 consecutive immunocompromised patients, nine with AIDS and 29 with other causes of immunosuppression, were characterized and compared. PCP in patients without AIDS was diagnosed after a significantly shorter time interval from symptom onset: 8 +/- 6 vs. 18 +/- 1.0 days (p = 0.024). From a radiographic point of view, non-AIDS patients had a significantly higher proportion of diffuse ground glass lesions, 86 vs. 44% (p = 0.02), and a lower proportion of cystic lesions, 3 vs. 56% (p = 0.015). The two subgroups did not differ in smoking status and the number of pack-years. On multivariant analysis, only the presence of AIDS was found to be a risk factor for the formation of pulmonary cystic lesions. Different immune reactions to the parasite P. jirovecii in immunocompromised patients with and without AIDS results in a different time lag between symptoms and a correspondingly different radiographic pattern: widespread ground glass opacities in the former and cystic lesions in the latter.