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.