OBJECTIVETo study the clinicopathologic features and differential diagnosis of cryptogenic organizing pneumonia (COP).

METHODSThe clinical, radiologic and pathologic features of 11 patients with COP confirmed by open or video-assisted thoracoscopic (VATS) lung biopsy were analyzed. Treatment information and follow-up data were also obtained.

RESULTSCOP usually affected female patients over 40 years of age. Clinical presentations included cough, sputum and exertional dyspnea. High-resolution computerized tomography showed scattered speckled, patchy and trabecular shadows over both lung fields. Honeycomb changes were not found. Histologically, polypoid growths of granulation tissue were noted within respiratory bronchioles, small airways and alveolar spaces. These lesions had a patchy and peribronchiolar distribution and were uniform in appearance. The overall response rate to glucocorticoid was 81.8% (P < 0.01). The duration of follow up ranged from 6 to 134 months. Apart from one patient who developed aggravation of symptoms, the disease pursued a relatively stable clinical course.

CONCLUSIONSIn general, COP responds well to glucocorticoid therapy. Open or VATS lung biopsy is important for arriving at a definitive diagnosis, especially for those cases presenting with atypical clinical and radiographic manifestations. Multiple biopsies with larger samples are preferred in order to avoid misdiagnosis.