Factors associated with the relapse of cryptogenic and secondary organizing pneumonia

Organizing pneumonia (OP) is a histopathological response pattern to lung inflammation. It is clinically classified into cryptogenic OP and secondary OP, which is associated with various clinical conditions. Rapid resolution with corticosteroids and frequent relapses are common in OP. However, few studies have investigated the factors associated with OP relapse.

The medical records of 75 patients with biopsy-proven OP, diagnosed between January 2010 and August 2015, who underwent corticosteroid therapy were retrospectively reviewed. Initially, the patients were all treated successfully; however, 31 patients experienced relapse thereafter (R group), whereas the others did not (NR group; 44 patients). The clinical, radiological, and pathological characteristics and administered corticosteroid doses were compared between the two groups.

The neutrophil percentage in the bronchoalveolar lavage (BAL) fluid and the level of fibrin deposition in lung biopsy specimens were higher in the R group than in the NR group (P=0.01 and P=0.002, respectively). The multivariate analysis demonstrated that both factors were statistically significant predictors of OP relapse.

A high neutrophil percentage in the BAL and the level of fibrin deposition in lung biopsy specimens are considered predictive factors of OP relapse during the tapering or after the cessation of steroid therapy. Patients without these findings may be treated with low-dose corticosteroids.