A low-grade (WHO grade II) astrocytic neoplasm. It is characterized by diffuse infiltration of neighboring central nervous system structures. These lesions typically affect young adults and have a tendency for progression to anaplastic astrocytoma and glioblastoma. Based on the IDH genes mutation status, diffuse astrocytomas are classified as IDH-mutant, IDH-wildtype, and not otherwise specified. The disease is Monarch Disease Ontology entry MONDO_0016686 (diffuse astrocytoma). Also known as: WHO grade II astrocytoma, astrocytoma, diffuse, astrocytoma, diffuse, malignant, grade II astrocytic neoplasm, grade II astrocytic tumor, grade II astrocytic tumour, grade II astrocytoma.