Chronic eosinophilic pneumonia

Chronic eosinophilic pneumonia (CEP) is an idiopathic condition characterised by the alveoli filling with an inflammatory, eosinophil-rich infiltrate. Classically on imaging, it appears as chronic consolidation with upper zone and peripheral predominance.

Most patients are middle aged, and approximately 50% have background asthma. There is a greater female predilection 1.

It is often insidious with symptoms averaging several months before diagnosis. 

The diagnosis is usually based on the association of:

  • respiratory symptoms of usually more than 2 weeks duration
  • alveolar and/or blood eosinophilia (alveolar eosinophilia ≥ 40% at bronchoalveolar lavage (BAL) differential cell count; blood eosinophilia ≥ 1000/mm3)
  • pulmonary infiltrates with usually a peripheral predominance on chest imaging
  • exclusion of any known cause of eosinophilic lung disease

Histology typically shows accumulation of eosinophils and lymphocytes in the alveoli and interstitium, with interstitial fibrosis. An organizing pneumonia pattern or an eosinophilic abscess may also be seen. Lung function tests can be normal in mild cases but usually show restrictive defects. Peripheral blood eosinophilia is usually mild or moderate but occasionally can be severe.

  • increased serum IgE levels can be seen in two-thirds of patients
  • the erythrocyte sedimentation rate (ESR) is usually elevated
  • peripheral blood thrombocytosis has also been reported
  • the percentage of eosinophils in the BAL fluid is very high

There is nonsegmental peripheral airspace consolidation (“photographic negative shadow of pulmonary oedema” -  see reverse bat wing appearance) involving mainly the upper lobes but may only be seen in less than half of cases.

CT demonstrates typical non-segmental areas of airspace consolidation with peripheral predominance. There may be a middle or upper zone predilection 2.

Less common findings predominate in later stages of disease and includes

Later imaging, e.g. 2 months after the onset of symptoms, may also show linear bandlike opacities parallel to the pleural surface or lobar atelectasis 4. This vertical band is not interrupted by the pulmonary fissures.

In <10% of cases, a pleural effusion may be observed.

The long-term prognosis is considered excellent but the majority often will require long-term low-dose oral corticosteroid therapy in order to prevent relapse 7-8.

It was first described by C B Carrington et.al in 1969 3-6.

For CT imaging appearances, consider

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Article information

rID: 19123
System: Chest
Section: Pathology
Synonyms or Alternate Spellings:
  • Chronic eosinophilic pneumonitis
  • Chronic eosinophilic pneumonia (CEP)
  • Idiopathic chronic eosinophilic pneumonia (ICEP)
  • Idiopathic chronic eosinophilic pneumonia
  • Carrington's disease
  • Carrington disease

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