Eosinophilic Pneumonia

Common symptoms include a cough, fever, dyspnea, night sweats.

Acute eosinophilic pneumonia follows a rapid course with symptoms developing within two weeks. Myalgias and pleuritic chest pain with dyspnea may also be present, which can progress to respiratory failure. These patients can present with apparent acute lung injury or acute respiratory distress syndrome (ARDS) without any antecedent illness. However, extrapulmonary failure and shock are absent, which differentiates it from ARDS. On auscultation, diffuse crackles are present.

Chronic eosinophilic pneumonia follows a progressive course. The presentation is subacute with symptoms present for months before diagnosis. These patients present with moderate weight loss besides the common symptoms. Over time, dyspnea progresses and presents with wheezing, especially in those with adult-onset asthma.

Idiopathic Acute eosinophilic pneumonia- is usually a diagnosis of exclusion. 

• Eosinophilia on BAL (>25% eosinophils)
• Marked leukocytosis, but blood eosinophilia is initially not common
• Serum IgE may be moderately elevated
• Pulmonary function tests reveal restrictive ventilatory defect with reduced DLCO
• Nonspecific chest radiographs with subtle ground-glass opacities - bilateral diffuse mixed ground-glass opacities develop as the disease progresses
• Small to moderate bilateral pleural effusions are common
• CT scan confirms the diagnosis but usually not required
• Fluid analysis- High pH and marked eosinophilia

Chronic eosinophilic pneumonia - the diagnosis is based on clinical, radiographic, and BAL findings and on the inability to document pulmonary or systemic infection.

• Marked eosinophilia on bronchoalveolar lavage, typically accounting for more than 40 percent of white blood cells
• Moderate leukocytosis with peripheral blood eosinophilia in most patients
• Serum IgE levels elevation is a feature in half of the patients
• Moderate normocytic, normochromic anemia with thrombocytosis is present.
• ESR is typically elevated
• Pulmonary function tests depend on the severity of the disease; it may be restrictive, obstructive, or normal.
• Peripheral infiltrates on chest radiographs. Infiltrates are mostly bilateral, located in mid and upper lung zones.[12]

Supportive care with supplemental oxygen and glucocorticoids are the initial management in acute cases. While waiting for the culture results, starting mechanical ventilation and empiric antibiotics are valid therapeutic measures.

Systemic glucocorticoid therapy (intravenous or oral) is recommended for all and started as soon as possible for rapid improvement within 12-48 hours. However, the dose depends on the severity. Without glucocorticoid therapy, there is a risk of progressive respiratory failure in acute eosinophilic pneumonia patients. Once the respiratory failure resolves, oral prednisone continued for 2-4 weeks with a subsequent slow taper over the next few weeks.

There is a dramatic response to corticosteroids with rapid resolution of symptoms within an hour and complete resolution of infiltrates within a month.

For chronic eosinophilic pneumonia, prednisone (40-60 mg) until two weeks after the resolution of symptoms and x-ray abnormalities. Treatment is maintained for at least three months and optimally for 6 to 9 months. Some patients may require longer maintenance. Later, inhaled corticosteroids can be started allowing discontinuation of oral steroids.[12][13]

• Asthma/allergy
• Broncho-centric granulomatosis
• Bronchiolitis obliterans organizing pneumonia
• Infections - fungal (Coccidioidal infection, Aspergillus, Pneumocystis jirovecii)
• Interstitial lung diseases
• Malignancy[13][14]

Once the diagnosis of acute eosinophilic pneumonia is established, and corticosteroid treatment started, the prognosis is excellent with a dramatic response to therapy.

Sometimes prolonged glucocorticoid therapy may be required when there is a risk of recurrence; the prognosis is generally good for patients with chronic eosinophilic pneumonia.[15] 

Eosinophilic pneumonia affects the lung and is predominantly idiopathic. It requires interprofessional care and the involvement of more than one subspecialty. This patient-centered approach involving a primary care provider with a team of other health professionals, including a pulmonologist, physiotherapists, respiratory therapists, nurses, pharmacists, and support groups working together for the patient, plays a vital role in improving the quality of care in pneumonia patients. Critical care nurses monitor patients, administer treatment, and are crucial to team communication. Pharmacists counsel patients about the importance of compliance with glucocorticoids and educate them about the side effects. The timely diagnosis and treatment are crucial, especially in patients with an acute presentation, as left untreated, it can progress to respiratory failure. [Level 5]