A Rare Presentation of Bilateral Foot Drop in Anti-neutrophil Cytoplasmic Antibody (ANCA)-Negative Eosinophilic Granulomatosis With Polyangiitis (Churg-Strauss Syndrome): A Diagnostic Challenge.

Eosinophilic granulomatosis with polyangiitis (EGPA), known as Churg-Strauss syndrome, is a rare multisystem vasculitis mainly affecting small- to medium-sized vessels. It is characterized by eosinophil-rich granulomatous inflammation and necrotizing vasculitis. EGPA is considered a part of the ANCA-associated vasculitis (AAVs), but it also shares features with hypereosinophilic syndrome (HES), reflecting the dual contributions of vascular inflammation and eosinophilic tissue infiltration to organ damage. This case report describes a 65-year-old male presenting with progressive bilateral foot drop and marked eosinophilia, ultimately diagnosed with EGPA. His symptoms included sensorimotor deficits and purpuric skin lesions. Investigations revealed mononeuritis multiplex, significant eosinophilia, and pulmonary involvement. The patient was started on high-dose corticosteroids followed by cyclophosphamide, which led to marked clinical improvement.  This case underscores the importance of early recognition and management of EGPA, highlighting its varied clinical manifestations and the potential for favorable outcomes with appropriate management.