PRL and myeloid sarcoma: In the entire mixed cohort of MS patients (n = 36), by applying robust linear regression, we found a positive correlation between PRL and disease duration in months (coef;0.017, p = 0.013) and various MRI features indicative of high lesion burden (e.g. volume of periventricular lesions; coef;2.97, p < 0.01 and Supplementary Tables 1–2).