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What is Anaplastic astrocytoma and explain in detail?
Anaplastic astrocytoma is a rare WHO grade III type of astrocytoma, which is a type of cancer of the brain. In the United States, the annual incidence rate for anaplastic astrocytoma is 0.44 per 100,000 people.

Signs and symptoms
Initial presenting symptoms most commonly are headache, depressed mental status, focal neurological deficits, and/or seizures. The growth rate and mean interval between onset of symptoms and diagnosis is approximately 1.5–2 years but is highly variable, being intermediate between that of low-grade astrocytomas and glioblastomas. Seizures are less common among patients with anaplastic astrocytomas compared to low-grade lesions.

Causes
Most high-grade gliomas occur sporadically or without identifiable cause. However, a small proportion (less than 5%) of persons with malignant astrocytoma have a definite or suspected hereditary predisposition. The main hereditary predispositions are mainly neurofibromatosis type I, Li-Fraumeni syndrome, hereditary nonpolyposis colorectal cancer and tuberous sclerosis. Anaplastic astrocytomas have also been associated with previous exposure to vinyl chloride and to high doses of radiation therapy to the brain.

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

Treatment
The standard initial treatment is to remove as much of the tumor as possible without worsening neurologic deficits