NEFL and progressive pseudorheumatoid arthropathy of childhood: While blood NfL has shown strong diagnostic performance in distinguishing PPD from specific ND subtypes, such as behavioral variant frontotemporal dementia (bvFTD),8, 9, 21, 22, 23, 24 broader comparative studies across diverse ND and PPD populations are needed to fully realize its clinical utility and for real‐world clinical translation.