Microscopic polyangiitis is a small-vessel necrotizing vasculitis associated with anti-neutrophil cytoplasmic antibodies and presents itself with glomerulonephritis and hemorrhagic pulmonary capillaritis. Peripheral nervous system involvement is common in anti-neutrophil cytoplasmic antibodies-associated vasculitis, but brachial plexopathy is unusual. We present the case of a 22-year-old man with known microscopic polyangiitis who was under maintenance therapy with prednisolone and cyclophosphamide and developed cough, dyspnea, and hemoptysis which increased in 6 days accompanying pain and paresthesia in the upper limbs. His physical examination revealed hypoesthesia, absence of deep tendon reflexes, and decreased muscle strength in the upper limbs. His chest computed tomography scan showed ground glass pattern in the lower and middle lobes. Electromyography and nerve conduction study showed bilateral brachial plexopathy with involvement of all of the cervical roots that were more severe in the lower roots and left side.
Keywords: Brachial plexopathy; Microscopic polyangiitis; Vasculitis.