What is the initial approach to treating pneumonitis?

Initial Approach to Treating Pneumonitis

The initial approach to treating pneumonitis should be based on severity grading, with discontinuation of the suspected causative agent and initiation of corticosteroid therapy for grade 1-2 pneumonitis, while grade 3-4 pneumonitis requires hospitalization, permanent discontinuation of the offending agent, and high-dose intravenous corticosteroids. 1

Diagnosis and Assessment

• CT chest imaging is the preferred diagnostic modality to identify ground-glass opacities, patchy nodular infiltrates, or interstitial patterns characteristic of pneumonitis 1
• Bronchoscopy with bronchoalveolar lavage (BAL) should be performed to exclude infections, especially in grade 2 or higher pneumonitis 1
• Transbronchial or surgical lung biopsy may be considered when the etiology is unclear, though not routinely required 1

Treatment Algorithm Based on Severity

Grade 1 (Asymptomatic)

• Close monitoring while continuing therapy, particularly for patients with isolated radiologic changes 1
• Monitor symptoms every 2-3 days 1, 2
• Weekly clinical visits for evaluation 2
• No corticosteroid treatment required at this stage 2

Grade 1-2 (Mild to Moderate)

• Discontinue the suspected causative agent 1
• Initiate oral corticosteroids with prednisone 1 mg/kg daily or equivalent 1
• Taper steroids over 4-6 weeks after recovery 1

Grade 3-4 (Severe to Life-threatening)

• Hospitalize the patient 1
• Permanently discontinue the offending agent 1
• Administer high-dose intravenous corticosteroids (methylprednisolone 2-4 mg/kg/day or equivalent) 1
• Consider additional immunosuppressive strategies, such as infliximab, mycophenolate mofetil (MMF), or cyclophosphamide, if no improvement after 48 hours 1
• For immune checkpoint inhibitor (ICI) pneumonitis, administer broad-spectrum antibiotics in parallel to immunosuppressive treatment if infectious status cannot be reliably assessed 1

Special Considerations

• Improvement following cessation of drug administration without glucocorticoid therapy strongly supports the diagnosis of drug-related pneumonitis 1
• For immune checkpoint inhibitor-related pneumonitis, steroid tapering should be very slow (6+ weeks) as relapses during tapering have been reported 1
• Patients with cancer, particularly non-small cell lung cancer (NSCLC) and renal cell carcinoma (RCC), have higher risk of developing pneumonitis than patients with melanoma 2
• The incidence of pneumonitis is higher in patients receiving combination immunotherapy compared to monotherapy (10% vs 3%) 2

Warning Signs for Treatment Escalation

• Development of respiratory symptoms such as cough, dyspnea, or chest pain 2
• Decrease in oxygen saturation 2
• Radiographic progression of pulmonary lesions 2

Long-term Management

• For hypersensitivity pneumonitis, early diagnosis and avoidance of further exposure to the causative agent are key elements in management 3, 4
• Patients with fibrotic hypersensitivity pneumonitis may demonstrate a decline in lung function over time despite immunosuppression, suggesting antifibrotic therapy may be a better initial choice in these cases 5
• Approximately 2% of patients with immunotherapy-related toxicity experience chronic pneumonitis that persists despite discontinuation of the causative agent 2