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anaplastic_astrocytoma

Anaplastic astrocytoma

Anaplastic astrocytoma (AA) is a diffusely infiltrating, malignant, astrocytic, primary brain tumor.

Compared to grade II tumors, anaplastic astrocytomas are more cellular, demonstrate more atypia, and mitosis are seen.

IDH mutation & diffuse astrocytoma/anaplastic astrocytoma. IDH-wildtype is rare both for diffuse astrocytoma (some of these may turn out to be lower grade lesions such as gangliogliomas) and for anaplastic astrocytoma (some of which may be glioblastomas). Some, 1) but not all, 2) studies show little prognostic difference between IDH-mutant Grade II and Grade III astrocytomas. But IDH-mutant cases appear to do better than IDH-wildtype for both diffuse and anaplastic astrocytomas.

Tumors may lose their IDH mutation over time.

Epidemiology

The overall age-standardized incidence is 3.5 per million person years with a peak incidence of 8 per million population in the 75 to 79 year age group.

Classification

see Anaplastic astrocytoma classification.

see Spinal cord anaplastic astrocytoma

Diagnosis

By CT or MRI complex enhancement some may not enhance. Most glioblastomas enhance, but some rare ones do not.

Pathology

Histology: compared to WHO grade II astrocytomas, there is a high degree of cellularity and increased mitotic activity (more than a few mitoses in a resection specimen), often along with additional signs of anaplasia (distinct nuclear atypia, multinucleated tumor cells & abnormal mitoses). These tumors stain positive for GFAP.

Molecular genetics

ATRX & TP53 mutations are present in the majority of these tumors and support the diagnosis.

Neuroradiology

Anaplastic astrocytomas (AA) often exhibit complex enhancement on CT or MRI; however, some may not enhance. 3).

Ring enhancement as is typical in glioblastoma does not occur. Calcifications and cysts are seen in 10–20% of AA 4).

Management

see Anaplastic astrocytoma management.

Outcome

Anaplastic astrocytomas fall under the category of high grade gliomas (WHO grade III-IV), which are pathologically undifferentiated gliomas that carry a poor clinical prognosis. Unlike glioblastomas (WHO grade IV), anaplastic astrocytomas lack vascular proliferation and necrosis on pathologic evaluation.

Case reports

Anaplastic astrocytoma case reports.

1)
Reuss DE, Mamatjan Y, Schrimpf D, et al. IDH mutant diffuse and anaplastic astrocytomas have similar age at presentation and little difference in survival: a grading problem for WHO. Acta Neuropathol. 2015; 129:867–873
2)
illela PJ, Pirozzi CJ, Healy P, et al. Mutations in IDH1, IDH2, and in the TERT promoter define clin- ically distinct subgroups of adult malignant glio- mas. Oncotarget. 2014; 5:1515–1525
3) , 4)
Narayan P, Olson JJ. Management of anaplastic astrocytoma. Contemp Neurosurg. 2001; 23:1–6
anaplastic_astrocytoma.txt · Last modified: 2020/01/28 16:26 by administrador