MYD88 L265P mutation in neurologic autoimmunity without evidence of malignancy.

MYD88 mutation status is assessed in the evaluation of CNS lymphoma since the mutation MYD88 L265P is highly predictive of this disease. However, whether the MYD88 L265P mutation may lead to other diseases outside of malignancy is not well understood. Here we describe two patients with the MYD88 L265P mutation in the CSF with no additional evidence of neoplastic disease but were found to have two distinct neurologic autoimmune conditions (anti-GFAP astrocytopathy and multiple sclerosis). These cases suggest this activating mutation may predispose certain patients to autoimmune conditions and may have future therapeutic implications.