Title : Rapidly progressive asymmetric vasculitic neuropathy revealing eosinophilic granulomatosis with polyangiitis: A diagnostic challenge
Abstract:
Introduction: Eosinophilic granulomatosis with polyangiitis (EGPA), formerly known as Churg–Strauss syndrome, is a rare ANCA-associated necrotizing vasculitis characterized by eosinophilia, pulmonary involvement, extravascular granulomatous inflammation and multisystem disease. Peripheral nervous system involvement is common during the vasculitic phase; however, rapidly progressive asymmetric neuropathy as the initial major manifestation may represent a significant diagnostic challenge.
Case Presentation: A 64-year-old man presented with acute-onset weakness of the right hand, which progressed within several days to involve the contralateral upper extremity, resulting in rapidly progressive asymmetric motor deficits. His medical history was notable for poorly controlled diabetes mellitus and cholestatic liver disease. Several months before admission, he had undergone evaluation for chronic cough and a pulmonary nodule; positron emission tomography/computed tomography demonstrated only a metabolically inactive cystic lesion.
Neurological examination revealed marked asymmetric weakness predominantly affecting both upper extremities. Electrodiagnostic studies demonstrated severe axonal sensorimotor neuropathy with polyradiculoneuropathic involvement. Cranial and spinal magnetic resonance imaging, together with cerebrospinal fluid analysis, failed to identify an alternative explanation for the rapidly progressive neurological deficits.
The coexistence of diabetes mellitus, pulmonary abnormalities and positive Brucella agglutination test (Coombs method) represented plausible competing diagnostic considerations; therefore, infectious, metabolic and other more common etiologies were initially prioritized during the diagnostic work-up. Despite antimicrobial therapy and seven sessions of plasma exchange, neurological deficits continued to progress.
Subsequent investigations demonstrated marked peripheral eosinophilia (peak eosinophil count: 38%), positive p ANCA, biclonal gammopathy and elevated serum kappa and lambda free light chains. Sural nerve biopsy revealed fibrinoid necrosis of epineurial vessels with mononuclear inflammatory infiltrates and marked loss of myelinated fibers, confirming vasculitic neuropathy. Peripheral nerve biopsy played a pivotal role in establishing the diagnosis, and EGPA was diagnosed based on the clinical, laboratory and histopathological findings. High-dose corticosteroidbased immunosuppressive therapy was initiated.
Following treatment, muscle strength improved to Medical Research Council (MRC) grade 5/5 in all proximal and distal muscle groups except for the wrist extensors, which remained at MRC grade 2/5. The patient continues to
undergo rehabilitation for persistent wrist extensor weakness.
