TNFSF13B and myeloid sarcoma: A statistically significant association between the level of serum BAFF protein in MS patients negative to EBNA1400–413 and BAFF serum levels in MS patients positive to: EBNA1 (Dunn’s multiple comparison test, p = 0.02, Fig. 3A), EBNA1 negative and positive under MP treatment (Dunn’s multiple comparison test, p = 0.0031 and p = 0.0062, respectively; Fig. 3A) was observed.