Chronic Eosinophilic Pneumonia: Causes, Symptoms, Diagnosis, and Treatment of This Rare Eosinophilic Lung Disease

on

Chronic Eosinophilic Pneumonia: Causes, Symptoms, Diagnosis, and Treatment of This Rare Eosinophilic Lung Disease

Introduction

Chronic Eosinophilic Pneumonia (CEP) is a rare yet clinically significant pulmonary condition, often associated with asthma and allergic rhinitis. Its presentation can mimic more common diseases, leading to diagnostic challenges. This column provides an in-depth review of CEP, including its etiology, pathophysiology, clinical and radiological features, treatment options, prognosis, and relevant visual cases. 

Etiology and Pathogenesis

CEP is characterized by an abnormal accumulation of eosinophils in the lung interstitium and alveolar spaces. While the exact etiology remains unclear, it is often idiopathic. However, a strong correlation exists between CEP and atopic conditions, such as asthma and allergic rhinitis. Immunologic dysregulation, involving overproduction of interleukin-5 (IL-5) and eotaxins, contributes to eosinophilic infiltration and inflammation of the pulmonary parenchyma.

Epidemiology

CEP is an uncommon disorder, predominantly affecting middle-aged women (30-50 years), especially those with a history of asthma. Non-smokers are disproportionately affected, and there is no known racial or geographic predilection. Despite its rarity, increased awareness and high-resolution imaging have led to improved diagnosis rates in recent years.

Clinical Presentation

Patients typically present with subacute respiratory symptoms:

  • Persistent nonproductive cough

  • Progressive dyspnea

  • Wheezing

  • Chest tightness

  • Systemic manifestations like fever, night sweats, weight loss, and malaise

A striking feature is the presence of constitutional symptoms alongside respiratory complaints, often resembling infectious pneumonia but refractory to antibiotics.

Case Highlight: A 54-year-old woman with asthma and allergic rhinitis presented with severe cough and dyspnea for three months, accompanied by fever, night sweats, and unintentional weight loss of 9 kg. Her absolute eosinophil count was elevated at 5,240/μL.

Imaging Features

Radiographic and CT findings are pivotal in diagnosing CEP:

Figure 1. Chest P-A X-ray reveals bilateral peripheral airspace opacities.

Figure 1: Chest X-ray showing bilateral peripheral consolidation, suggestive of CEP.

Figure 2. High-resolution chest CT demonstrates upper-lobe-predominant, subpleural, and peripheral consolidations sparing the perihilar regions.

Figure 2: CT scan highlighting subpleural consolidation characteristic of CEP.

This radiologic pattern is classically described as the “photographic negative of pulmonary edema.”

Figure 3. Follow-up chest X-ray after corticosteroid treatment shows significant radiological improvement.

Figure 3: Radiographic resolution after corticosteroid therapy.

Laboratory and Diagnostic Workup

  • Eosinophilia: Peripheral eosinophil count >1,500/μL (typically markedly elevated)

  • BAL (Bronchoalveolar Lavage): Elevated eosinophils (>25%, often >40%)

  • Negative infectious workup: Rule out parasitic, fungal, or mycobacterial infections

  • Negative autoimmune markers: Rule out ANCA-associated vasculitis

Differential Diagnosis

  • Acute eosinophilic pneumonia

  • Allergic bronchopulmonary aspergillosis (ABPA)

  • Hypereosinophilic syndrome

  • Parasitic infections

  • Drug-induced pneumonitis

  • Organizing pneumonia

Treatment and Management

First-line therapy:

  • Systemic corticosteroids (Prednisone): 0.5 to 1 mg/kg/day for several weeks, followed by a taper

Response:

  • Clinical symptoms usually improve within days

  • Radiological resolution typically follows within 2-3 weeks

Long-term management:

  • Monitor for relapse (common if steroids are tapered too quickly)

  • Some patients may require low-dose maintenance therapy

Case Resolution: In our case, the patient was treated with oral prednisone. After 17 days, her symptoms and radiologic findings showed remarkable improvement. She remained relapse-free during a five-month follow-up.

Prognosis

With appropriate corticosteroid therapy, the prognosis of CEP is generally excellent. However, relapse rates may exceed 50% if tapering is rapid. Rarely, a long-standing disease may cause irreversible fibrosis.

Quiz Section

1: Which radiological pattern is characteristic of Chronic Eosinophilic Pneumonia?

A) Central consolidation with pleural effusion

B) Photographic negative of pulmonary edema

C) Nodular upper lobe infiltrates

D) Cavitary lesion in upper lobe

2: What is the most appropriate initial treatment for CEP?

A) Broad-spectrum antibiotics

B) Bronchodilators

C) Oral corticosteroids

D) Antifungal agents

3: Which of the following is most commonly associated with CEP?

A) Smoking

B) Chronic obstructive pulmonary disease (COPD)

C) Asthma

D) Tuberculosis

4: What is the typical eosinophil percentage found in BAL fluid in CEP?

A) <2%

B) 5-10%

C) 10-25%

D) >40%

Answer & Explanation

1. Answer: B) Photographic negative of pulmonary edema. Explanation: CEP often presents with peripheral, upper-lobe predominant consolidations, sparing the perihilar area—hence the classic 'photographic negative of pulmonary edema.

2. Answer: C) Oral corticosteroids. Explanation: Corticosteroids are the cornerstone of CEP treatment, leading to rapid clinical and radiological improvement.

3. Answer: C) Asthma. Explanation: A majority of CEP patients have a history of asthma or allergic conditions, which is a strong predisposing factor.

4. Answer: D) >40%. Explanation: BAL fluid in CEP often shows markedly elevated eosinophils, usually above 40%, which aids in diagnosis.

Conclusion

Chronic Eosinophilic Pneumonia is a treatable and often curable pulmonary disorder if promptly diagnosed and managed. The hallmark imaging findings, eosinophilia, and favorable steroid response distinguish it from other interstitial lung diseases. Continuous awareness and clinical suspicion are vital for early diagnosis and preventing recurrence.

References

[1] J. C. Allen, "Chronic eosinophilic pneumonia: diagnosis and management," Chest, vol. 117, no. 5, pp. 1484–1491, 2000.
[2] M. Marchand et al., "Idiopathic chronic eosinophilic pneumonia: a clinical and follow-up study of 62 cases," Medicine (Baltimore), vol. 77, no. 5, pp. 299–312, 1998.
[3] A. J. Katzenstein, "Eosinophilic lung diseases," Arch Pathol Lab Med, vol. 134, no. 6, pp. 819–824, 2010.
[4] T. Cottin, "Eosinophilic lung diseases," Clin Chest Med, vol. 37, no. 3, pp. 535–556, 2016.
[5] S. J. Allen et al., "Eosinophilic lung diseases: a clinical overview," Am J Med, vol. 123, no. 7, pp. 619–627, 2010.
[6] G. Cordier, "Eosinophilic pneumonias," Eur Respir J, vol. 22, no. 5, pp. 646–653, 2003.
[7] S. Marchand and D. Cordier, "Idiopathic chronic eosinophilic pneumonia," Orphanet J Rare Dis, vol. 1, article 11, 2006.

Comments

Post a Comment