Diffuse Alveolar Hemorrhage (DAH) Secondary to Influenza B in a Kidney Transplant Recipient with Anti-glomerular Basement Membrane (Anti-GBM) Disease

Introduction: DAH is a potentially life-threatening syndrome requiring immediate recognition and treatment. In kidney transplant recipients with known Anti-GBM disease in native kidneys, recurrent anti-GBM disease should be suspected if they present with microscopic hematuria, proteinuria, and/or acute kidney injury. However, isolated DAH is rare and poses a diagnostic challenge, particularly if it is secondary to infection. Case Description: A 48-year-old male with Anti-GBM disease presented to the emergency department with hemoptysis. He had been diagnosed with Anti-GBM disease twelve years earlier, resulting in rapidly progressive glomerulonephritis that was refractory to first and second-line treatments. He became dialysis dependant until his kidney transplant 10 years later. His disease had remained quiescent since transplant and his allograft function was normal on immunosuppression. Upon presentation, his vitals were stable except for a temperature of 100.5 F. Chest radiography revealed infiltrates in the left middle and lower lung lobes. A computed tomography (CT) scan of the chest confirmed these infiltrates and showed surrounding ground glass opacities. Serum electrolytes, creatinine and urinalysis were normal. Bronchoscopy revealed progressively bloody aliquots consistent with DAH. He was treated with daily plasmapheresis for possible recurrent disease for 2 days. This treatment was discontinued when his serum Anti-GBM antibody returned negative, and no evidence of anti-GBM disease was found on lung pathology. Consequently, his DAH was suspected to be secondary to viral pneumonia, specifically Influenza B, and all treatments except antiviral therapy were discontinued. Discussion: Isolated DAH in a patient with Anti-GBM disease is typically either an initial presentation or an indicator of disease recurrence. However, in this case, the patient presented with alveolar hemorrhage without laboratory findings suggestive of disease recurrence, indicating that the DAH was secondary to viral pneumonia. Infection, although rare, should be considered a possible cause of DAH once more common causes have been excluded. This case highlights the importance of considering infectious etiologies in patients with DAH. Early identification and appropriate management of the underlying cause are crucial for improving patient outcomes.