Cryptogenic organizing pneumonia: CT findings in 43 patients.

OBJECTIVE: Description of the CT findings of cryptogenic organizing pneumonia has been limited to a small number of cases. This study was performed to characterize the CT findings of this disease in a larger number of cases and to compare the findings in immunocompetent and immunocompromised patients. MATERIALS AND METHODS: The CT scans of 43 (32 immunocompetent and 11 immunocompromised) patients who had biopsy-proved cryptogenic organizing pneumonia were reviewed. The scans were obtained by using contiguous 8- or 10-mm collimation and selected thin (1.5 or 2.0 mm) section (n = 23), thin-section collimation at 10-mm intervals (n = 12), or 8- or 10-mm collimation only (n = 8). The scans were analyzed by three observers, and final decisions were reached by consensus. RESULTS: The most common pattern seen was consolidation, which was present alone or as part of a mixed pattern in 34 cases (79%). The consolidation had a predominantly subpleural and/or peribronchovascular distribution in 27 cases (63%). Ground-glass attenuation and nodules were seen in 26 patients (60%) and 13 patients (30%), respectively, and were usually random in distribution. Consolidation was present in 91% (29/32) of immunocompetent and 45% (5/11) of immunocompromised patients (p .25). Nodules were present in seven (22%) of 32 immunocompetent patients and six (55%) of 11 immunocompromised patients (p < .025). CONCLUSION: We conclude that in immunocompetent patients the CT findings in cryptogenic organizing pneumonia most commonly consist of bilateral areas of consolidation involving mainly the subpleural and/or peribronchovascular regions. In the immunocompromised patient, the CT findings are variable.