CREB1 and primary progressive multiple sclerosis: In contrast, PPMS is characterized by positivity for EMA, along with negativity for desmin and ALK. Moreover, low-to-intermediate malignant potential AFH can also exhibit EWSR1::CREB1 fusion due to t(2; 22) (q33; q12) (Antonescu et al. 2007; Costa and Weiss 1990).