Chronic eosinophilic pneumonia (CEP) is a disorder characterized by an abnormal and marked accumulation of eosinophils in the lung . CEP can often present as a fulminant illness with a constellation of symptoms including cough, fever, progressive breathlessness, weight loss, wheezing, and night sweats . Other characteristics of CEP include the following:
- Asthma accompanies, precedes, or subsequently occurs, in over 50 percent of cases . A majority of patients are nonsmokers.
- The finding of bilateral peripheral or pleural-based opacities described as the "photographic negative" of pulmonary edema is virtually pathognomonic for the disease when seen on chest radiograph (image 1) or high resolution computed tomography (picture 1) .
- Peripheral blood eosinophilia (>6 percent), a very high sedimentation rate, C-reactive protein, iron deficiency anemia, and thrombocytosis are all common laboratory abnormalities .
- Bronchoalveolar lavage (BAL) eosinophilia of greater than 25 percent is suggestive of CEP [5,6]. These eosinophils appear to be activated, as evidenced by the presence of several different markers of activation, including increased release of eosinophil proteins . Serial BAL examinations may be helpful in following the course of the disease but is rarely indicated .
- Histopathologic findings are characterized by interstitial and alveolar eosinophils and histiocytes, including multinucleated giant cells. Fibrosis is minimal, and bronchiolitis obliterans with organizing pneumonia is a common associated finding (picture 2).
In this review, the treatment of chronic eosinophilic pneumonia and response to therapy are discussed. The evaluation and differential diagnosis of eosinophilic lung diseases, in general, and an approach to acute eosinophilic pneumonia are described separately. (See "Causes of pulmonary eosinophilia" and "Idiopathic acute eosinophilic pneumonia".)
Fewer than 10 percent of patients with CEP spontaneously recover or improve. In addition, CEP occasionally leads to physiologically important, irreversible fibrosis , although death secondary to CEP is extremely unusual. As a result, therapy is indicated once alternative diagnoses of eosinophilic infiltration of the lung are excluded (particularly infectious causes).
Patients with CEP are uniformly responsive to intravenous or oral glucocorticoids. Thus, an alternative diagnosis should be entertained if a patient is steroid-resistant.