Acute Eosinophilic Pneumonia
Related Subjects: Asthma
|Acute Severe Asthma
|Eosinophilic granulomatosis (Churg-Strauss)
|Loffler's syndrome (Pulmonary Eosinophilia)
|Pulmonary Eosinophilia and CXR changes
|Drug Reaction Eosinophilia Systemic Symptoms
ℹ️ About
- Acute Eosinophilic Pneumonia (AEP) is a rare respiratory condition of unknown aetiology characterized by the rapid onset of respiratory symptoms and pulmonary eosinophilia.
- There is an increased incidence among U.S. military personnel in Iraq, suggesting possible environmental or infectious triggers.
🧬 Aetiology
- The exact cause is unknown, but potential triggers include infectious agents, environmental exposures, and inhalation of toxins (e.g., dust, smoke, or chemicals).
- Often, no specific cause is identified, making the diagnosis challenging.
🩺 Clinical Features
- Rapidly progressive symptoms including increased dyspnoea, fever, and severe breathlessness.
- Other symptoms include cyanosis, cough, and production of phlegm.
- Patients often present with acute respiratory distress and may require urgent medical attention.
🔎 Investigations
- Blood Tests:
- Full Blood Count (FBC): Shows elevated white cell count (WCC) and increased inflammatory markers such as ESR and CRP.
- Peripheral Blood Eosinophilia: May be absent in early stages but often develops later.
- Arterial Blood Gas (ABG): Indicates Type 1 respiratory failure with hypoxemia.
- Imaging:
- Chest X-Ray (CXR): Reveals diffuse pulmonary infiltrates.
- CT Scan: Shows bilateral ground-glass opacities, interlobular septal thickening, and parenchymal consolidation, consistent with an acute inflammatory process.
- Bronchoalveolar Lavage (BAL): Essential for diagnosis, revealing >25% eosinophils, which is a key finding in AEP.
💊 Management
- Steroid Therapy: High-dose corticosteroids lead to a marked reduction in eosinophilia and rapid clinical improvement. However, initiating steroids before performing a BAL can obscure the diagnosis by reducing the eosinophil count in lavage samples.
- Supportive Care: Management of hypoxemia with supplemental oxygen or mechanical ventilation if required.
- Close monitoring is necessary due to the potential for rapid deterioration in respiratory function.
Prognosis
- With appropriate and timely treatment, most patients recover completely without long-term respiratory complications.
- Recurrence is rare, but some patients may require a prolonged tapering course of corticosteroids to prevent relapse.
References
3 Clinical Cases — Acute Eosinophilic Pneumonia (AEP) 🧪🫁
- Case 1 — New smoker 🚬: A 24-year-old man develops fever, myalgia, dry cough, and rapidly progressive dyspnoea 2 weeks after starting cigarette smoking. CXR: diffuse bilateral infiltrates. BAL: eosinophils >25%. Teaching: AEP is often triggered by new smoking exposure. Presents with ARDS-like picture but with BAL eosinophilia. Responds dramatically to corticosteroids with complete recovery.
- Case 2 — Occupational exposure 🏭: A 36-year-old woman working in a metal factory develops acute breathlessness and hypoxaemia after exposure to welding fumes. ABG: PaO₂ 6.9 kPa on air. CT: diffuse ground-glass opacities with interlobular septal thickening. Teaching: Inhalational exposures (dusts, fumes, smoke) can trigger AEP. BAL eosinophilia confirms diagnosis. Supportive care + high-dose steroids usually lead to rapid improvement.
- Case 3 — Drug-induced AEP 💊: A 42-year-old man treated with daptomycin for MRSA bacteraemia develops fever, hypoxaemia, and diffuse pulmonary infiltrates after 10 days of therapy. BAL: eosinophilia, peripheral eosinophil count rising. Teaching: Drugs (daptomycin, minocycline, NSAIDs, SSRIs) are recognised triggers of AEP. Key step is withdrawal of the culprit drug + corticosteroids. Prognosis is excellent if recognised early.
