anaplastic astrocytoma (grade 3)

Introduction

Astrocytoma with anaplasia (Grade 3).

Pathology

• increased cellularity
• nuclear atypia
• mitoses
• tend to progress to glioblastoma

Genetics

• chromosome 9p loss in 50% of anaplastic astrocytomas & GBMs primarily affecting CDKN2A gene
• chromosome 13q loss in 1/3 - 1/2 of high grade astrocytomas RB gene inactivated in 20% of anaplastic astrocytomas, 35% GBMs
• chromosome 12q13-14 amplification in 15% malignant gliomas including gene for CDK4
• allelic loss on chromosome 19q in up to 40% of anaplastic astrocytomas and GBMs
• diminished or absent expression of PHF3

Radiology

• magnetic resonance imaging (MRI)
• computed tomography (CT)
• higher grade astrocytomas show contrast enhancement

Management

• radiation
  • prolongs survival
  • 5000-6500 cGy
  • administered in multiple fractions to an area around the tumor
  • radiation necrosis may produce clinical picture indistinguishable from recurrent high-grade tumor
• dexamethasone
  • administered with radiation therapy
  • tapered to lowest dose after radiation
• chemotherapy (BCNU, CCNU) combined with radiation
  • treatment of choice (marginally effective)
• surgery
  • surgical excision is not possible because anaplastic astrocytomas infiltrate adjacent brain tissue
  • may be useful to reduce mass effect
  • stereotaxic radiosurgery with gamma knife
    • potential for tumor abalation
    • useful for tumors < 3 cm in diameter
• prognosis: 50% survival of 12 months (with radiation)

More general terms

• malignant glioma
• astrocytoma (astrocytic neoplasm)