High-grade astrocytoma with piloid features: MRI findings associated with a novel entity.

High-grade astrocytoma with piloid features is a newly defined brain tumor that requires DNA methylation profiling for diagnosis. Imaging features specific to this tumor have only recently been described in the radiological literature. We highlight the case of a 34-year-old man who presented with a 4-week history of headaches and light-headedness. Postresection, pathological analysis identified the tumor based on DNA methylation profiling, and the patient was started on adjuvant chemotherapy with Temozolomide. T2-weighted imaging showed a well-circumscribed cerebellar mass, which correlated with the pathology-reported glial tumor cells being elongated and piloid. T1-postgadolinium imaging showed heterogeneous enhancement of linear serpiginous areas, which correlated with regions of high microvascular density and vessels that showed thickening and hyalinization. Diffusion-weighted imaging and apparent diffusion coefficient mapping did not show significant diffusion restriction. Rosenthal fibres were absent. Given the specific imaging-pathology correlation, this report contributes imaging features associated with this novel diagnostic entity.