<prompt> Answer this question truthfullyWhat is the underlying pathological mechanism of gliomatosis cerebri?  <response>: <reason> Genes involved in pathogenesis of gliomatosis cerebri include: P53 Isocitrate dehydrogenase IDH1 OLIG-2 Ki-67 EGFR PTEN VCAM1 VEGF Gene on chromosome 7q Gene on chromosome 10q Gene on chromosome 13qGliomatosis cerebri may be associated with: Neurofibromatosis type 1 PilomatricomaOn gross pathology, gliomatosis cerebri is characterized by: Diffuse, usually astrocytic growth pattern Involvement of at least three lobes of the brain Bilateral involvement of the cerebral hemispheres, deep gray matter, brainstem, or cerebellumCommon intracranial sites involved in gliomatosis cerebri include: Basal and thalamic nuclei 75 Corpus callosum 50 Brainstem and spinal cord 10-15 Cerebellum 10 Two or more sites generally affected at the same timeOn microscopic histopathological examination, gliomatosis cerebri is characterized by: Diffuse proliferation of immature glial elements resembling astrocytes, oligodendroglia, or undifferentiated cells Cytologic and nuclear atypia Calcification Microcysts Mitotic figures No necrosis or microvascular proliferationAccording to WHO classification of brain tumors, gliomatosis cerebri is classified into grade 2 or grade 3 tumors.Gliomatosis cerebri is demonstrated by positivity to tumor markers such as GFAP, S-100, and Ki-67. 