Polyangiitis Overlap Syndrome: Polyarteritis Nodosa with Leukocytoclastic Vasculitis Associated with Left Ventricular Thrombus and Vocal Cord Palsy: A Case Report

Polyangiitis overlap syndrome (POS) is a systemic vasculitis characterized by overlapping features of more than one well-defined vasculitic syndrome. We present the case of a 38-year-old Malay man with progressive dyspnea and palpable purpura in his lower limbs. The diagnostic evaluation revealed right-sided segmental pulmonary consolidation with pleural effusion, systolic cardiac dysfunction with the presence of an intracardiac thrombus, and left vocal cord palsy secondary to laryngeal mononeuropathy. Anti-neutrophil cytoplasmic antibodies testing yielded negative results, and skin biopsy revealed leukocytoclastic vasculitis (LCV) with negative immunofluorescence studies. The patient fulfilled the American College of Rheumatology diagnostic criteria for polyarteritis nodosa and idiopathic LCV. Only three case reports of POS with a combination of polyarteritis nodosa overlapping with idiopathic LCV have been reported in the medical literature. To the best of our knowledge, this is the first report of POS with cardiopulmonary involvement and laryngeal mononeuropathy. This patient had an excellent response to remission induction therapy using high-dose corticosteroids and mycophenolate mofetil and remains in remission while undergoing a steroid taper. Timely initiation of treatment is essential to prevent vasculitic complications and irreversible organ dysfunction. Mycophenolate mofetil may serve as an acceptable alternative to cyclophosphamide as a remission induction agent in this condition.