Cryptogenic cerebral venous thrombosis in a multiple-sclerosis-patient treated with Alemtuzumab

Alemtuzumab is a highly effective treatment for relapsing-remitting multiple sclerosis (MS). Its molecular target is CD 52, a GPI-anchored protein. Herein, we describe the case of a 40-year-old man with MS treated with alemtuzumab, who developed cerebral sinus thrombosis. In the literature, alemtuzumab was associated with venous thrombosis, attributed to a paroxysmal nocturnal hemoglobinuria (PNH)-like mechanism. In our case, no PNH clones were detected. Other common causes of cerebral venous thrombosis, like infections and thrombophilia, were excluded, thus the pathogenic mechanism remains obscure.