Chronic Eosinophilic Pneumonia

Chronic eosinophilic pneumonia (CEP) is a subacute to chronic idiopathic disease with peripheral and alveolar eosinophilia and peripheral lung infiltrates.

Mean age 45 years; women affected twice as often as men; non smokers; about 50% have asthma or atopy.

Pathology: eosinophilic and lymphocytic infiltrate of alveoli and interstitium, with organising pneumonia.

Exclude drugs (nitrofurantoin, NSAIDs, amiodarone), parasites, fungi (ABPA), EGPA.

Relapses are frequent when steroids are tapered (50 to 80%).

• Subacute symptoms over weeks to months: cough, progressive dyspnoea, wheeze, fever, night sweats, weight loss, malaise.
• Asthma often precedes or coexists.
• Crackles and wheeze; extrapulmonary features (neuropathy, rash, sinusitis) suggest EGPA.

• Peripheral blood eosinophils 1000 cells/µL or more (present in about 90%), high ESR, CRP, IgE, thrombocytosis.
• Chest radiograph: bilateral peripheral upper zone airspace opacities ("photographic negative of pulmonary oedema"), seen in a minority; CT shows peripheral consolidation, ground glass.
• BAL eosinophils over 25% (often over 40%).
• Exclude secondary causes: stool studies, Strongyloides and Toxocara serology, Aspergillus IgE, ANCA, fungal and mycobacterial cultures, drug history.
• Lung biopsy if diagnosis uncertain.
• Spirometry: obstructive or restrictive; sinus CT; troponin and echo if cardiac concern.

• Prednisolone 0.5 mg/kg/day (30 to 40 mg) for 2 to 4 weeks, with rapid improvement within 24 to 72 hours (radiographic clearance in 1 to 2 weeks), then slow taper over 6 to 12 months to a maintenance dose (5 to 10 mg) because of relapse.
• Relapse: increase dose, add inhaled corticosteroids, steroid sparing therapy (azathioprine 2 mg/kg, mycophenolate, methotrexate), or anti IL 5 therapy (mepolizumab 100 to 300 mg every 4 weeks, benralizumab 30 mg every 4 to 8 weeks, reslizumab).
• Inhaled corticosteroids (budesonide/formoterol) for asthma component and to spare systemic steroids.
• Strongyloides exposure: ivermectin 200 micrograms/kg for 2 days before steroids.
• Monitor eosinophil count, ESR, CRP and imaging at 1, 3 and 6 months, then every 3 to 6 months.
• Pneumocystis prophylaxis during high dose or prolonged therapy, bone protection, vaccinations.
• Prognosis is excellent but long term maintenance may be required.