Analysis of the clinical characteristics of 176 patients with pathologically confirmed cryptogenic organizing pneumonia

Background Cryptogenic organizing pneumonia (COP), is a form of idiopathic interstitial pneumonia (IIP) and is diagnosed by clinical-radiologic-pathologic (CRP) diagnosis. To summarize the clinical, imaging, pathological, and prognostic characteristics of 176 patients with confirmed COP. Methods Patients who were diagnosed with organizing pneumonia (OP) by lung biopsy between January 1, 2000, and December 31, 2013, in our hospital were retrospectively analyzed and followed up until 12/31/2017. COP was confirmed by CRP diagnosis. Results A total of 1,346 OP cases were identified including 1,170 (86.9%) secondary OP cases (31 cases were originally misdiagnosed as COP but later confirmed as secondary OP during follow-up) and 176 (13.1%) cases of COP. The 176 patients with COP presented with no specific clinical symptoms and chest CT revealed diverse imaging features, such as patchy ground-glass opacity (112/176, 63.6%), consolidation (100/176, 56.8%), nodules (70/176, 39.8%), and fibrous stripes (69/176, 39.2%). The majority of patients (65.3%, 115/176) presented mixed patterns, and 12 (6.8%) showed a reversed halo sign. Of the 176 patients, 83 patients had unilateral lesions (ULs) and did not undergo glucocorticoid therapy. Of the 93 patients with bilateral lesions (BLs), 3 underwent complete resection and were radically cured. The other 90 patients underwent partial resection; of these patients, 37 cases achieved spontaneous remission, and 53 were treated with glucocorticoid therapy. After steroid therapy was reduced or stopped, 35 (66%) patients experienced recurrence. Overall, the 5-year survival rate for the COP patients in our study was 98.3%. Conclusions Our study showed that the majority of the patients pathologically diagnosed as OP had secondary OP (86.9%), with COP accounting for only 13.9% of cases. CRP diagnosis and continuous follow-up may be the key for the accurate diagnosis of COP.