Correct
4. Begin prednisone

The biopsy showed eosinophils and is consistent with eosinophilic pneumonia and possibly pulmonary fibrosis in the lower lobe biopsy. The collections of eosinophils are seen best in the higher power views (Figure 4).

Figure 4. VATS lung biopsy showing collections of eosinophils in higher power views (arrows).

Just as all that wheezes is not asthma, all eosinophilia is not asthma either. Causes of eosinophils in bronchoalveolar lavage fluid are listed in table 1.

Table 1. Causes of bronchoalveolar lavage eosinophilia

Eosinophilic pneumonia is divided into acute eosinophilic pneumonia and chronic eosinophilic pneumonia. Acute eosinophilic pneumonia is usually associated with:

• Respiratory symptoms of < 2 weeks
• Hypoxemia often causing acute respiratory failure and mimicking ARDS
• BAL eosinophilia is usually above 25%
• No or mild blood eosinophilia (<1000)
• Lung biopsy evidence of eosinopilic infiltrates (acute and/or organizing diffuse alveolar damage with prominent eosinophils).

In contrast, chronic eosinophilic pneumonia is associated with

• Respiratory symptoms > 2 weeks
• Alveolar eosinophilia (≥ 40% eos on BAL)
• Blood eosinophilia (often ≥1000)
• Pulmonary infiltrates usually with a peripheral predominance
• Twice as frequent in women as men
• A third to half have a history of asthma
• Less than 10% are active smokers
• Although dyspnea and cough are common, respiratory failure is rare

Both are diagnosis of exclusion and the treatment is corticosteroids. However, if biopsy is planned, corticosteroid use should be avoided since as little as a day or two of corticosteroids can result a marked decrease in the number of eosinophils on biopsy making diagnosis more difficult. Relapse is frequent in chronic but not in acute eosinophilic pneumonia.

This patient had evidence of eosinophilic pneumonia with some underlying histologic features of UIP. Some cases of chronic eosinophilic pneumonia have been reported to lead to pulmonary fibrosis. This is possible in the current patient, although the clinical history did not suggest prior respiratory symptoms. He was treated with corticosteroids (prednisone 60 mg/day) with subsequent decrease in some of abnormalities on chest radiograph, although there was evidence of some persistent fibrotic changes, particularly in the lung bases.

References

1. Allen JN, Davis WB, Pacht ER. Diagnostic significance of increased bronchoalveolar lavage fluid eosinophils. Am Rev Respir Dis 1990;142:642-7.
2. Tazelaar HD, Linz LJ, Colby TV, Myers JL, Limper AH. Acute eosinophilic pneumonia: histopathologic findings in nine patients. Am J Respir Crit Care Med. 1997;155:296-302.
3. Allen JN, Magro CM, King MA. The eosinophilic pneumonias. Semin Respir Crit Care Med 2002;23:127-34.
4. Alam M, Burki NK. Chronic eosinophilic pneumonia: a review. South Med J 2007;100:49-53.

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