An Unusual Manifestation of Fever, Eosinophilia, and Proximal Muscle Weakness: Idiopathic Eosinophilic Myositis Accompanied by Eosinophilic Vasculitis

Eosinophilia-associated myopathies exhibit clinical and pathological heterogeneity. This is a man in his sixties who presented with fever accompanied by prodromal symptoms, as well as bilateral lower limb weakness and pain. There was evidence of peripheral eosinophilia, increased CPK levels, polyphasic muscle action potentials, and eosinophilic infiltration into the muscle with eosinophilic vasculitis present, without cutaneous or myofascial involvement. Serological and imaging studies were unremarkable, revealing no discernible secondary aetiology for eosinophilia or myositis. A diagnosis of idiopathic eosinophilic myositis accompanied by eosinophilic vasculitis was established. He received glucocorticoids and methotrexate, resulting in effective symptom relief.