www.mingyihui.net Chronic Eosinophilic Pneumonia Medical Guide (Introduction)

**A Guide to Seeking Medical Care for Chronic Eosinophilic Pneumonia (Introduction)**

Chronic eosinophilic pneumonia (also known as chronic myelogenous pneumonia, chronic eosinophilic pneumonia, protracted eosinophilia, and persistent pulmonary eosinophilic infiltration) is a rare condition that affects the lungs.

### What is Chronic Eosinophilic Pneumonia?

Chronic eosinophilic pneumonia (CEP) is also referred to as protracted eosinophilia or chronic myelogenous pneumonia. The disease has a longer course compared to simple eosinophilia, typically lasting from 2 to 6 months, and sometimes over a year. Symptoms are generally more severe.

### Symptoms of Chronic Eosinophilic Pneumonia

This condition can occur at any age, but it is most common in individuals aged 30–40 years, with women being affected almost twice as often as men. Most cases involve Caucasians, and about one-third to one-half of patients have a history of allergic rhinitis or nasal polyps. Additionally, two-thirds of patients experience adult-onset asthma or other respiratory symptoms. Clinically, the disease presents subacutely, with common symptoms including low-grade fever, night sweats, moderate weight loss, cough, slight mucus production, and hemoptysis in some cases. Eventually, progressive dyspnea develops, often associated with episodic asthma. In rare cases, patients may present with acute severe respiratory failure or ARDS.

Diagnosis can be made based on medical history, disease progression, wheezing in both lungs, increased eosinophils in peripheral blood, and chest X-ray findings. For atypical cases, a lung biopsy may be necessary for definitive diagnosis. A trial of prednisone treatment can also assist in confirming the diagnosis.

### Diagnostic Tests for Chronic Eosinophilic Pneumonia

- **Blood tests**: Leukocytosis (>10×10^9/L). About 60%–90% of patients show an increase in peripheral blood eosinophils (>6%), though the absence of eosinophilia does not rule out the disease. Sputum analysis may reveal a high number of eosinophils. Increased erythrocyte sedimentation rate (>20mm/h) and elevated IgE levels in one-third of cases.

- **Pulmonary function tests**: Abnormalities vary depending on the stage of the disease, with typical cases showing moderate to severe restrictive ventilatory dysfunction and reduced DLCO.

- **Arterial-alveolar oxygen gradient**: Elevated, with obstructive changes if asthma is present.

- **Chest X-ray**: Shows progressive infiltrates near the pleura with unclear margins, non-segmental, subsegmental, and lobar distribution, predominantly in the outer two-thirds of the lungs. This creates a "reverse halo" appearance due to increased transparency around the hilum. Shadows tend to recur in the same location after resolution. Unlike Löffler's syndrome, CEP lung infiltrates are non-migratory, and pleural effusion is rare.

- **Chest CT**: Useful for cases with atypical X-ray findings. Early stages (within a few weeks) typically show areas of consolidation, while later stages (after 2 months) may exhibit fibrotic bands and enlarged mediastinal lymph nodes.

### Treatment Considerations for Chronic Eosinophilic Pneumonia

- **Treatment**: Prednisone is the primary treatment for CEP. Most patients respond rapidly to an initial dose of 40mg/day, with fever subsiding within 6 hours, improvement in dyspnea, cough, and eosinophilic infiltration within 24–48 hours, and relief of hypoxemia in 2–3 days. Radiographic improvement occurs within 1–2 weeks, with full symptom resolution in 2–3 weeks and complete radiographic resolution within 2 months. After clinical improvement, prednisone should be tapered gradually (over 10–14 days), with a total treatment duration of 4–6 months.

- **Prognosis**: The prognosis for CEP is generally good, though fatalities can occur. Untreated patients rarely experience spontaneous remission, but corticosteroid treatment significantly reduces mortality. However, rapid tapering or interruption of prednisone can lead to recurrence in 58%–80% of cases. Recurrences often occur in the same anatomical locations and may require treatment for 1–2 years. In some cases (25%), long-term maintenance therapy (2.5–10mg/day) may be necessary until the disease resolves. Although there are no specific indicators for predicting recurrence or the need for long-term treatment, short courses (1–3 months) often result in relapse, even multiple times. However, re-initiation of prednisone remains effective.

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