Fig. 7

Imaging features and histologic spectrum of unclassifiable LGNET harboring FGFR1 alterations. These tumors are unlikely to represent a unified group, and may likely represent either novel rare glioma subtypes or tumors that did not reliably cluster by methylation analysis due to low tumor content or other technical issues. Patient uLGNET #1 is a 47 year old woman with a heterogeneously enhancing, T2 hyperintense mass centered in the third ventricle. Histology demonstrated a low-grade glial neoplasm with solid growth pattern, mucin-rich stroma with frequent microcysts, and rare mitotic figures. Patient uLGNET #2 is a 26 year old female with a heterogeneously enhancing mass centered in the posterior horn of the lateral ventricle that was histologically composed of a low-grade oligodendroglial neoplasm with frequent microcalcifications and mucin-rich stroma, but lacked any well-defined neurocytic rosettes