Disease phenotype also was significantly associated with higher CSF NfL concentrations (p = 0.001), with higher concentrations in RRMS (median 2082 pg/ml, IQR 2652.07 pg/ml) than in CIS patients (median 1025.37 pg/ml, IQR 1141.43 pg/ml). Here, NEFL is linked to in situ carcinoma.