Lung, Chronic eosinophilic pneumonia

Chronic eosinophilic pneumonia is a rare form of idiopathic pneumonia characterized by accumulation of eosinophils. Peripheral blood eosinophilia and BAL eosinophilia are frequent laboratory abnormalities. The characteristic radiographic pattern consists of bilateral airspace consolidation confined to the lung periphery - a finding referred to as reversed pulmonary edema pattern. Histologic examination shows intra-alveolar eosinophils, macrophages and an amorphous proteinaceous exudate. Charcot-Leyden crystals may be present. Eosinophils infiltrate the interstitium in about the 60% of cases and an organizing pneumonia is present in 25%. Eosinophilic abscesses with foci of necrosis may also be present. There may be a mild chronic or eosinophilic vasculitis.