Stanford School of Medicine

Surgical Pathology Criteria

 use browser back button to return

Acute Eosinophilic Pneumonia


  • Acute respiratory insufficiency associated with pulmonary eosinophil infiltration

Covered Separately

Diagnostic Criteria


  • Acute onset of dyspnea, cough and fever
    • Rapid progression to respiratory insufficiency
    • Generally under 1-2 weeks
    • Presentation similar to diffuse alveolar damage / acute interstitial pneumonia
  • Mean age 30, usually previously healthy
  • Rapid response to steroids
    • Does not relapse


  • Bilateral diffuse opacities


  • Blood eosinophils usually normal
    • Occasionally elevated but generally <500/mm3
  • Demonstration of pulmonary eosinophilia required for diagnosis with either:
    • Bronchoalveolar lavage (BAL) fluid shows eosinophils > lymphocytes
      • Usually >25%
      • Other cells are macrophages and neutrophils
    • Tissue biopsy shows prominent eosinophilic infiltrate
      • Biopsy is not usually necessary for diagnosis but may help rule out infection
      • Intra-alveolar and usually interstitial
      • 5-25% eosinophils is consistent with diagnosis, >25% is suggestive
        • Eosinophils are rare in normal lung (<2%)
      • Changes of diffuse alveolar damage with hyaline membranes usually present
      • Changes of cryptogenic organizing pneumonia (BOOP) frequently present
  • Known causes must be ruled out
    • Drugs including antibiotics, non-steroidal anti-inflammatory, anti-hypertensive, heroin, cocaine
    • Organisms including fungi and parasites

Gerald J Berry MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates: 11/20/10

Differential Diagnosis

Simple Eosinophilic Pneumonia Acute Eosinophilic Pneumonia Chronic Eosinophilic Pneumonia
Asymptomatic to mild symptoms Fulminant respiratory insufficiency Chronic dyspnea, cough
Blood eosinophils mildly elevated Blood eosinophils normal to mildly elevated Blood eosinophils >1000/mm3
No direct treatment required Steroid responsive, no relapses Steroid responsive, 50% relapse


Known causes of eosinophilic pneumonia must be ruled out

  • Drugs
    • Check history
    • Skin rash suggestive
  • Organisms
    • Check travel history
    • Check stool ova and parasites
    • Check serology for fungi and parasites
    • Culture and stain lavage and biopsy specimens
    • Allergic bronchopulmonary aspergillosis
      • Bronchiolocentric
      • May have necrotizing granulomatous bronchiolitis
      • Mucus plugs common
      • Culture, serology, biopsy identification


Acute Interstitial Pneumonia / Diffuse Alveolar Damage Acute Eosinophilic Pneumonia
Eosinophils infrequent Prominent eosinophils in lavage and biopsy specimens
Not steroid responsive, poor prognosis Steroid responsive, no relapses
Diffuse alveolar damage pattern may be seen in acute eosinophilic pneumonia


Cryptogenic Organizing Pneumonia (BOOP) Acute Eosinophilic Pneumonia
Subacute onset Acute, fulminant onset
Eosinophils infrequent Prominent eosinophils in lavage and biopsy specimens
BOOP pattern may be seen in acute eosinophilic pneumonia


Desquamative Interstitial Pneumonia Acute Eosinophilic Pneumonia
Subacute onset Acute, fulminant onset
Eosinophils infrequent Prominent eosinophils in lavage and biopsy specimens
Following steroid treatment, eosinophils may be harder to identify

Classification / Lists

Idiopathic Interstitial Lung Diseases

Other Diffuse Parenchymal Lung Diseases



  • Travis WD, Colby TV, Koss MN, Rosado-de-Christenson ML, Müller NL, King TE Jr.  Non-neoplastic Disorders of the Lower Respiratory Tract, AFIP Atlas of Nontumor Pathology, First Series, Fascicle 2, 2002.
  • 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 Jan;155(1):296-302.
  • Pope-Harman AL, Davis WB, Allen ED, Christoforidis AJ, Allen JN. Acute eosinophilic pneumonia. A summary of 15 cases and review of the literature. Medicine (Baltimore). 1996 Nov;75(6):334-42.
  • Jederlinic PJ, Sicilian L, Gaensler EA. Chronic eosinophilic pneumonia. A report of 19 cases and a review of the literature. Medicine (Baltimore). 1988 May;67(3):154-62.
  • Marchand E, Cordier JF. Idiopathic chronic eosinophilic pneumonia. Orphanet J Rare Dis. 2006 Apr 6;1:11..
Printed from Surgical Pathology Criteria:
© 2009  Stanford University School of Medicine