ANCA-associated life-threatening systemic vasculitis after alemtuzumab treatment for multiple sclerosis.

Alemtuzumab is highly effective in relapsing remitting multiple sclerosis (RRMS), but autoimmune adverse events are of concern. In contrast to rare cases of immune-mediated cutaneous vasculitis, systemic vasculitis after alemtuzumab has not yet been described. We report the case of a 29-year-old man with RRMS who developed fever, auricular chondritis, cutaneous vasculitis and life-threatening diffuse alveolar haemorrhage, 12 months after alemtuzumab. Antibodies to myeloperoxidase appeared 9 months after alemtuzumab and were extremely high at the time of vasculitis. Outcome was favourable after glucocorticoids, plasma exchanges and rituximab. Thus, alemtuzumab may induce life-threatening vasculitis in patients treated for RRMS.