diffuse astrocytoma fibrillary astrocytoma true NCIT:C4322 ICDO:9420/3 DOID:6726 MONDO:0016688 fibrillary astrocytoma The most frequent histological variant of diffuse astrocytoma. It is predominantly composed of fibrillary neoplastic astrocytes. Nuclear atypia is a diagnostic criterion but mitotic activity, necrosis and microvascular proliferation are absent. The occasional or regional occurrence of gemistocytic neoplastic cells is compatible with the diagnosis of fibrillary astrocytoma. (WHO) UMLS:C0334582 https://www.epilepsy.com/learn/professionals/co-existing-disorders/brain-tumors/astrocytoma ICD10:C71.9 Orphanet:251601 MedDRA:10065889 diffuse astrocytoma fibrillary astrocytic tumors