Clinical outcomes in patients with acute eosinophilic pneumonia not treated with corticosteroids.

Purpose: The objective of this study was to evaluate the course of clinical stability in patients with acute eosinophilic pneumonia (AEP) who did not receive corticosteroid treatment.

Methods: Secondary analysis included 19 consecutive patients with AEP who did not receive corticosteroid treatment from a cohort of 310 patients newly diagnosed with AEP between October 2007 and December 2013.

Results: All patients presented with dyspnea, fever, or cough with diffuse pulmonary infiltration. All but one patient (95 %) had elevated C-reactive protein (CRP), and 11 (58 %) patients had peripheral eosinophilia at the time of diagnosis. During the follow-up period, the dyspnea improved within a median of 4 (3-6) days and defervescence occurred within a median of 5 (4-7) days. Median time to clinical stability (defined as disappearance of all initial presenting symptoms) was 9 (7-12) days. In addition, the majority of pulmonary infiltrates on chest radiographs completely disappeared within 14 days after diagnosis. However, the peripheral eosinophil count and the frequency of peripheral eosinophilia increased up to 10 days and then decreased during the follow-up period. All patients experienced peripheral eosinophilia during hospitalisation.

Conclusion: AEP-associated symptoms and radiographic abnormalities were resolved completely within 2 weeks after diagnosis even when corticosteroid treatment was not initiated. However, these findings might be limited to relatively mild cases of AEP.