Eosinophilic Granulomatosis with Polyangiitis that was Difficult to Distinguish from Peroneal Nerve Palsy and Lumbar Disc Herniation: A Case Report

INTRODUCTION: Eosinophilic granulomatosis with polyangiitis (EGPA) patients with mononeuropathy multiplex often visit orthopedic clinics; however, orthopedic surgeons have limited experience in diagnosing EGPA because of its rarity. We report a case of EGPA that required 1 month to confirm the diagnosis. CASE REPORT: A 48-year-old woman presented with acute onset numbness in the right lower extremity. She had muscle weakness of the right lower extremity; lumbar spine magnetic resonance imaging showed lumbar disc herniation. Despite conservative treatment, her symptoms worsened. Blood tests showed increased eosinophils and serum IgE. She was diagnosed with EGPA, which should be considered in case of atypical paralytic symptoms. CONCLUSION: EGPA is so difficult to diagnose. In our case, the symptoms worsened on the 30th day after the initial visit. She was diagnosed with EGPA by a blood test at the time of admission. If patients with bronchial asthma or a history of allergies develop lumbar radiculopathy or peroneal nerve palsy-like symptoms, EGPA should be considered, and steroid treatment should be initiated early.