Epidemiology

• Sex: 2-fold more common in females
• Age: peak incidence in 30’s (but can occur at any age)
• More chronic clinical presentation (>14 days of symptoms) than [[Acute Eosinophilic Pneumonia]]
• Associated With:
  • Asthma/Atopic Diseases: pre-existing atopic disease (especially asthma) is present in 50% of cases
  • IBD: ulcerative colitis

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Physiology

• Unclear

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Pathology

Pathologic Patterns

• Eosinophilic Pneumonia: interstitial and alveolar eosinophil infiltration
  • Macrophages and multinucleated giant cells (giant cells may contain eosinophil fragments and crystals, which may be early Charcot-Leyden crystals)
  • Large Charcot-Leyden crystals and features of BO and vasculitis may also be seen in some cases
• Usual Interstitial Pneumonia (UIP): may be seen in some cases
• BOOP/Organizing Pneumonia Features/Cellular Interstitial Pneumonia (CIP): seen in some cases
• Honeycombing: seen late

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Diagnosis

CBC

• Eosinophilia (absent in about 15% of cases): mean peripheral eosinophil count is around 26%
• Neutrophilia and anemia (usually)

Sputum

• Eosinophilia

ABG

• Hypoxemia

PFT’s

• Obstructive Defect/Hyperinflation: may be seen

FOB

• BAL: eosinophilia >40% (normal <2%) is highly suggestive of eosinophilic pneumonia (BAL eosinophilia is nearly always seen, even when peripheral eosinophilia is absent)
• TBB: may be diagnostic

OLB

• Not needed in most cases (but may be useful to rule out BOOP)

CXR/Chest CT Patterns

• Alveolar infiltrates:
  -“Reverse Pulmonary Edema” (”Photographic Negative of Pulmonary Edema”) With Upper Lobe-Predominant Peripheral Infiltrates: occurs in 66% of cases
  • Infiltrates maay be fleeting and may not conform to lobar or segmental boundaries
  • Hilar adenopathy may be seen
  • Similar pattern may be seen in BOOP
• Interstitial infiltrates: may be superimposed on alveolar infiltrates later in course

Serum IgE

• Normal-mildly elevated

Circulating Immune Complexes

• Positive

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Clinical

(generally subacute illness that may persist for weeks-months in untreated cases/some cases present with acute respiratory failure)

• Wheezing: reported in some cases (generally recent onset)
• Cough: dry or mucoid sputum
• Dyspnea:
• Weight loss:
• Night sweats:
• Hemoptysis: occasional
• Fever:
• Lymphadenopathy:
• Hepatomegaly:

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Treatment

• Steroids: rapid resolution of symptoms and infiltrates (although mean latency to clinical response is 18 days)
  • Prednisone 30-60 mg/day will result in CXR improvement within 3 days (clearing within 3 weeks)
  • Taper steroids, follow for relapse (may occur)
  • Mean Duration of Therapy: 5 years

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Prognosis

• Long-term prognosis is good

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References

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