What is the initial approach to treating pneumonitis?

Management of Pneumonitis

The initial approach to treating pneumonitis should include discontinuation of the suspected causative agent and initiation of oral corticosteroids with prednisone 1 mg/kg daily or equivalent for grade 1-2 pneumonitis. 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 remains unclear, though not routinely required 1

Treatment Algorithm Based on Severity

Grade 1 (Asymptomatic)

• Close monitoring while potentially continuing therapy, particularly for patients with isolated radiologic changes 1
• Monitor symptoms every 2-3 days using pulse oximetry 1, 2
• Schedule weekly clinical visits for evaluation 2
• No corticosteroids required at this stage 2

Grade 1-2 (Mild to Moderate Symptoms)

• 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 clinical recovery 1
• Monitor for signs of improvement or deterioration 1

Grade 3-4 (Severe Symptoms)

• Hospitalize the patient immediately 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 (infliximab, mycophenolate mofetil, or cyclophosphamide) if no improvement after 48 hours 1
• For immune checkpoint inhibitor 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
• Clinical improvement with glucocorticoid therapy supports but does not definitively confirm 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 and renal cell carcinoma, have higher risk of developing pneumonitis than patients with melanoma 2
• The incidence of pneumonitis is higher in patients receiving combination immune checkpoint inhibitors compared to monotherapy (10% vs 3%) 2

Warning Signs for Treatment Escalation

• Development of respiratory symptoms (cough, dyspnea, chest pain) 2
• Decrease in oxygen saturation 2
• Radiographic progression of pulmonary lesions 2
• Lack of improvement after 48-72 hours of appropriate therapy 3

Non-Responding Pneumonitis

• If no improvement occurs within 48-72 hours, reassess the medical history, review microbiological data, and consider additional imaging such as high-resolution CT 3
• Consider alternative diagnoses including resistant pathogens, fungal infections, pulmonary embolism, malignancy, or vasculitis 3
• For fibrotic hypersensitivity pneumonitis, antifibrotic therapy may be more beneficial than immunosuppression 4
• Patients with extensive ground glass opacities may show improvement in diffusion capacity over one year with or without immunosuppression 4