Cryptogenic Organizing Pneumonia: Serial High-Resolution CT Findings in 22 Patients

OBJECTIVE. We conducted a review of serial high-resolution CT (HRCT) findings of cryptogenic organizing pneumonia (COP). MATERIALS AND METHODS. Over the course of 14 years, we saw 32 patients with biopsy-confirmed COP. Serial HRCT scans were available for only 22 patients (seven men and 15 women; mean age, 52 years; median follow-up period, 8 months; range, 5-135 months). Serial CT scans were evaluated by two chest radiologists who reached a conclusion by consensus. Overall changes in disease extent were classified as cured, improved (i.e., >= 10% decrease in extent), not changed, or progressed (i.e., >= 10% increase in extent). When there were remaining abnormalities, the final follow-up CT images were analyzed to express observers' ideas regarding what type of interstitial lung disease the images most likely suggested. RESULTS. The two most common patterns of lung abnormality on initial scans were ground-glass opacification (86% of patients [19/22]) and consolidation (77% of patients [17/22]), distributed along the bronchovascular bundles or subpleural lungs in 13 patients (59%). In six patients (27%), the disease disappeared completely; in 15 patients (68%), the disease was decreased in extent; and in one patient (5%), no change in extent was detected on follow-up CT. When lesions remained, the final follow-up CT findings were reminiscent of fibrotic nonspecific interstitial pneumonia in 10 of 16 patients (63%). CONCLUSION. Although COP is a disease with a generally good prognosis, most patients (73%) with COP have some remaining disease seen on follow-up CT scans, and, in such cases, the lesions generally resemble a fibrotic nonspecific interstitial pneumonia pattern.