This is a case report of someone with MS-associated fulminant tumefactive demyelinating lesion (TDL) with the special feature of delayed humoral or antibody immune response. Plasma exchange* (PE) yielded significant benefit in two consecutive steroid-unresponsive relapses, while signs of a B-cell response within the central nervous system were only present 2 years later at the second relapse. Remission was achieved and sustained thereafter with natalizumab. This case indicates that PE might be a therapeutic option even when the B-cell response is not fully developed. This delay in the development of a humoral or antibody immune response may reflect the step-wise B-cell colonization of the CNS and represent an attractive therapeutic window of opportunity.
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