Anaplastic astrocytoma is a rare, high-grade, malignant glial tumor, histologically characterized by abundance of pleomorphic astrocytes and multiple mitotic figures, often associated with diffuse infiltration of the surrounding tissue, considerable edema and mass effect and involvement of the contralateral brain. Depending on the primary localization of the tumor, patients can present with signs of raised intracranial pressure (headache, vomiting, papilledema), seizures, progressive neurological deficits, and/or behavioral changes. The tumor is most commonly localized in the frontal and temporal lobes, brain stem and spinal cord. The disease is Monarch Disease Ontology term MONDO_0016684 (anaplastic astrocytoma). Also known as: astrocytoma, anaplastic, malignant, grade III astrocytic neoplasm, grade III astrocytic tumor, grade III astrocytic tumour, grade III astrocytoma, malignant astrocytoma.