Introduction: Cryptogenic organizing pneumonia (COP) is a clinicopathologic syndrome characterized by a good prognosis with steroid therapy, but frequent relapses when the dose of corticosteroid is reduced or stopped.
Case report: The purpose of this study was to identify histopathologic features related to the relapse of COP. Six cases of COP that had been diagnosed using open lung biopsy were selected for evaluation. The 6 cases were put into two groups composed of 3 patients who relapsed and 3 who did not relapse. Their pathologic features were examined and compared.
Conclusions: Interstitial fibrosis of the lung parenchyma could correspond to histopathologic characteristics of relapses in COP.