Of note, complete absence of plasma cells, which are the source of CSF-restricted OCBs, as well as sparing of the cortex and basal ganglia, have also been reported in Marburg’s acute 'variant of MS' [72]; in line with that finding, the patient had neither OCBs nor quantitative evidence of intrathecal IgG, immunoglobulin M (IgM) or immunoglobulin A (IgA) synthesis. The gene discussed is CD79A; the disease is myeloid sarcoma.