Eosinophilic pneumonia is a clinical syndrome characterized by pulmonary eosinophilic infiltration, with or without peripheral blood eosinophilia. It can result from known causes, such as simple pulmonary eosinophilic infiltration (Löffler's syndrome), tropical pulmonary eosinophilia, allergic bronchopulmonary aspergillosis, or drug- or toxin-induced eosinophilia. It can also occur as an idiopathic condition, including acute eosinophilic pneumonia, chronic eosinophilic pneumonia, and eosinophilic granulomatosis with polyangiitis.
Chronic eosinophilic pneumonia (CEP) is of unknown etiology and most commonly affects middle-aged females. It typically presents with symptoms such as dyspnea, cough, fever, diaphoresis, weight loss, and wheezing over the course of weeks to months, following a subacute or chronic course.
The classic chest X-ray finding is dense alveolar infiltrates in the peripheral lung zones with central sparing, a pattern known as the photographic negative of pulmonary edema sign. The infiltrative lesions are often located in the upper lobes. Peripheral blood eosinophilia is observed in 80% of patients, and elevated serum IgE levels are also common.
If a patient presents with corresponding clinical and radiological features, and bronchoalveolar lavage fluid (BALF) shows eosinophilia greater than 40%, eosinophilic pneumonia is highly suspected.
The primary treatment is glucocorticoids.