anaplastic astrocytoma
Pronunciation: AN-ah-plas-tik AS-troh-sy-TOH-mah
WHO grade III astrocytic tumor characterized by increased cellularity, nuclear atypia, and mitotic activity.
Full Definition
A malignant primary brain tumor classified as WHO grade III that represents the intermediate grade between diffuse astrocytoma (grade II) and glioblastoma (grade IV). Anaplastic astrocytomas demonstrate increased cellularity, nuclear pleomorphism, and mitotic activity compared to lower-grade tumors, but lack the microvascular proliferation and necrosis characteristic of glioblastoma. Modern classification incorporates molecular markers, particularly IDH mutation and 1p/19q codeletion status, which significantly influence prognosis and treatment decisions. Standard treatment includes maximal safe resection followed by concurrent radiation therapy and temozolomide chemotherapy.
Usage
Usage note: May be abbreviated as AA; molecular markers are essential for accurate diagnosis and treatment planning.
In Context
- "The tumor was reclassified as anaplastic astrocytoma after molecular testing revealed IDH mutation without 1p/19q codeletion." — pathology amendment
- "Treatment of anaplastic astrocytoma follows the Stupp protocol with concurrent radiation and temozolomide." — treatment planning