C42-20 Hydralazine-induced Antineutrophil Cytoplasmic Antibodies Associated Vasculitis Presenting With Diffuse Alveolar Hemorrhage

Abstract Introduction Hydralazine is a commonly prescribed antihypertensive agent that, though effective, has been associated with rare autoimmune complications such as drug-induced lupus and antineutrophil cytoplasmic antibody (ANCA) associated vasculitis (AAV). Hydralazine-induced AAV can manifest with severe, life-threatening complications including diffuse alveolar hemorrhage (DAH) and rapidly progressive glomerulonephritis. Because these clinical features can mimic primary vasculitic syndromes or infectious processes, early recognition and discontinuation of the offending agent are vital. Case Presentation A 75-year-old man with chronic kidney disease, diabetes mellitus, hypertension (treated with hydralazine since 2018), and atrial fibrillation presented with a two-month history of progressive renal dysfunction. Two years earlier, he had demonstrated a mildly positive myeloperoxidase (MPO) antibody, with a renal biopsy at that time showing only diabetic nephropathy. On current presentation, autoimmune serologies were positive for antinuclear antibody (ANA), MPO, and anti-histone antibodies, findings consistent with drug-induced AAV. Hydralazine was discontinued, and high-dose daily intravenous methylprednisolone was initiated. On fourth day of infusion, patient presented to the emergency department with acute hemoptysis, dyspnea, and hypoxia requiring emergent intubation. Imaging revealed bilateral patchy opacities consistent with DAH. Laboratory evaluation showed worsening renal function (creatinine 3.48 mg/dL increased from baseline of 1.3), anemia (hemoglobin 6.2 g/dL), and thrombocytopenia (platelets 126 K/µL). Plasmapheresis was initiated urgently, followed by rituximab therapy. Renal biopsy demonstrated pauci-immune focal segmental crescentic glomerulonephritis superimposed on diabetic glomerulosclerosis, with acute tubular injury and red blood cell casts, confirming AAV in the setting of positive anti histone and MPO antibodies. The patient’s respiratory and renal status improved with treatment, allowing extubation and discharge on a gradual prednisone taper. Discussion Hydralazine-induced AAV is an uncommon but severe autoimmune disorder that can affect multiple organ systems. Risk factors include prolonged therapy, high cumulative doses, female sex, and concomitant autoimmune serologies such as anti-histone antibodies. DAH represents a particularly severe manifestation, necessitating prompt recognition and management. Primary AAV can have autoantibody positivity that precede symptoms by months to years, serving as an early warning for the development of vasculitis. Even though it has not been reported in any drug-induced AAV cases, if incidentally found, it may warrant close follow-up or drug cessation to avoid serious, potentially fatal complications. Conclusion This case underscores the importance of maintaining high clinical suspicion for hydralazine-induced AAV in patients on long-term therapy presenting with pulmonary or renal dysfunction. Early drug withdrawal and immunosuppressive therapy are crucial for improving outcomes and preventing life-threatening complications. This abstract is funded by: None