What are astrocytic and oligodendrocytic gliomas? high grade and low grade gliomas?

➢ Defined by the type of tumor cell and by the histological grade: histological aspects correlated with less differentiation and greater aggressiveness. ➢The grade follows the WHO classification : from grade I to grade IV ➢ Anaplasia (malignant transformation of the tumor) characterizes a highgrade tumor ➢We contrast circumscribed Gliomas which are usually benign (grade I) to infiltrating gliomas which can be either low grade (II) or high grade (malignant: grade III and IV). ➢ The most common circumscribed glioma is Pilocytic astrocytoma; it occurs in children