Representative immunohistochemical staining of neurofilament light polypeptide (NEFL). Immunostaining was scored from − to++on a subjective scale. Twenty‐five percent to 100% of cells staining yielded a score of++. Very focal staining in individual cells yielded a score of+. Absence of staining was given a − designation. A. Photomicrograph of a pediatric myxopapillary ependymoma (MEPN) with strong and diffuse cytoplasmic staining in fibrillary areas of tumor, scored as ++. Immunohistochemistry for NEFL with light hematoxylin counterstain, original magnification 200×. B. Photomicrograph at higher power shows the perivascular, perpendicularly oriented cell processes surrounding hyalinized blood vessels strongly immunoreactive for NEFL; this adult MEPN achieved a ++ score. Immunohistochemistry for NEFL with light hematoxylin counterstain, original magnification 400×. C. Photomicrograph of a pediatric MEPN showing strong, diffuse cytoplasmic staining in areas of the tumor with ependymal, epithelial, non‐fibrillary morphological features; this case scored as ++. Immunohistochemistry for NEFL with light hematoxylin counterstain, original magnification 400×. D. Photomicrograph of an adult MEPN with ++ diffuse immunoreactivity and slightly less intensity. Immunohistochemistry for NEFL with light hematoxylin counterstain, original magnification 400×. E. Focal immunostaining for NEFL in an adult MEPN, yielding a + score. Immunohistochemistry for NEFL with light hematoxylin counterstain, original magnification 400×. F. All subependymomas manifested absence of NEFL staining, as illustrated in this adult example. Immunohistochemistry for NEFL with light hematoxylin counterstain, original magnification 200×.