 However, considering parameters other than mortality, there is some evidence to suggest that patients with high pO2 concentrations benefit from adjunctive corticosteroids. PCP is associated with the development of pulmonary fibrosis and this can have significant consequences. Pathological studies have shown the development of interstitial fibrosis late in the course of acute illness. Studies have documented the presence of diffuse interstitial pneumonitis five months after the onset of acute illness. Therefore, patients with PCP infection, regardless of their pO2 level on presentation may benefit from corticosteroid therapy. 