Two cases of acute myelitis with idiopathic hypereosinophilic syndrome.

Idiopathic hypereosinophilic syndrome (IHES) is characterised by persistent eosinophilia and organ damage after ruling out other causes. IHES is clinically and pathologically heterogeneous, and several disease mechanisms have been described. Although neurological involvement with IHES is extremely rare, we report the first cases of acute myelitis with IHES, which are confirmed using MRI, fulfil the diagnostic criteria of IHES and pathologically reveal eosinophilic tissue infiltration in the liver and skin. Patient 1 had longitudinally extensive transverse myelitis, which developed in the absence of steroid therapy. Patient 2 developed acute myelitis with two short lesions during a 3 mg/day corticosteroid treatment. Both cases had eosinophilia (>1500/mm(3)) at the onset of myelitis. These findings suggest that earlier treatment and a sufficient dose of corticosteroids may prevent the lesional expansion in acute myelitis. Steroid therapy should be initiated early before organ involvement, because permanent neuronal damage with a larger lesion becomes more critical. 2014 BMJ Publishing Group Ltd.