Abstract Body (Do not enter title and authors here): Introduction:
Drug induced lupus (DIL) is an autoimmune reaction triggered by medication, mimicking systemic lupus erythematosus with symptoms like arthralgia, fever, and malar rash. Systemic vasculitis and pericarditis with pericardial effusion secondary to DIL are rare conditions with only a few reported cases and have been linked to ANCA positivity. We present a case of hydralazine-induced lupus (HIL) manifesting as ANCA vasculitis and persistent pericarditis.

Case Presentation:
49-year-old male with history of hypertension, non-ischemic cardiomyopathy, chronic kidney disease stage IIIa, and migratory polyarthritis presented with chest discomfort exacerbated by lying supine. Troponin was negative and BNP elevated at 1,600. ECG showed ST-T wave changes with PR depressions concerning for pericarditis. ESR was 122 mm/hr and CRP 78 mg/dL. Transthoracic echocardiogram revealed a small (<1 cm) circumferential pericardial effusion. Autoimmune titers showed ANA of 1:5120, anti-histone (7.8), anti-PR3 (80), and anti-MPO (800). Urinalysis revealed hematuria (2+), proteinuria (2+), and sediment. Renal biopsy revealed moderate interstitial fibrosis and tubular atrophy. Hydralazine was discontinued and colchicine with prednisone was started. He was then treated outpatient for HIL with associated vasculitis on long-term prednisone taper and rituximab. Repeat labs showed decreased anti-histone (2.3), anti-PR-3 (<1), anti-MPO (233), ESR 48 mm/hr and CRP 9.5 mg/dL. Despite these improvements on immunosuppressive therapy, he experienced persistent pleuritic chest pain, prompting a cardiac MRI that showed chronic pericarditis likely secondary to HIL. He is awaiting additional therapy in conjunction with prednisone and rituximab for further treatment.

Discussion:
The drugs most implicated in DIL include hydralazine, procainamide, and isoniazid. Pericardial involvement and vasculitis occurs in <5% of patients with HIL and is associated with anti-histone, anti-PR3, and anti-MPO. Persistent pericarditis despite normalized inflammatory markers in autoimmune conditions usually resolves within weeks to months although rarely may evolve into chronic autoimmune pericarditis. While no definitive management guidelines exist, treatment generally involves discontinuation of hydralazine although long-term immunosuppressive therapy may be needed.