astrocytoma (astrocytic neoplasm)
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Introduction
Epidemiology
- account for about 80% of adult primary brain tumors
- diffuse astrocytomas in general are most common in late middle age with the peak incidence of anaplastic astrocytomas occurring in the 6th decade
- glioblastoma multiforme: peak incidence in 7th decade
Pathology
- large & heterogenous group of tumors, with wide differences in their clinical incidence, gross & microscopic features, & biological behavior
- morphological diversity is attributable partly to the various structural forms displayed by developing, mature & reactive astrocytes, & to the propensity of neoplastic cells to accommodate their shape to the persistence of pre-existing structures in the neural parenchyma
- marked tendency to become more anaplastic with time
- a tumor initially diagnosed as a diffuse astrocytoma frequently proves on later biopsy to be anaplastic astrocytoma or glioblastoma
Microscopic pathology
- fibrillary/gemistocytic/protoplasmic astrocytomas:
- three grades of progressively increasing anaplasia & rapidity of clinical progression:
- diffuse astrocytoma (grade 2)
- anaplastic astrocytoma (grade 3)
- glioblastoma multiforme (grade 4)
- histologic features associated with higher grade
- hypercellularity
- nuclear & cytoplasmic atypia
- endothelial proliferation*
- mitotic activity
- necrosis*
- diagnostic criteria for grading (WHO/St. Anne-Mayo):
- cellular atypia
- mitotic activity
- endothelial proliferation
- necrosis One of the above findings is sufficient for grade II Two are sufficient for grade III Three are sufficient for grade IV (glioblastoma) * best indicators of aggressive behavior
Genetics
- defects in CAMTA1 associated with oligodendroglioma & astrocytoma
- diminished or absent expression of PHF3
- overexpression of TRIM47
- other implicated genes
Radiology
- magnetic resonance imaging[5]
- infiltrating white matter lesion
- contrast enhacement suggests higher grade astrocytoma
Management
- neurosurgery
- whole brain radiation therapy
- chemotherapy is controversial[5]
Prognosis:
- 3-8 years depending grade of astrocytoma
More general terms
More specific terms
- anaplastic astrocytoma (grade 3)
- astrocytic neoplasm, WHO grade 1
- diffuse astrocytoma (WHO grade 2)
- glioblastoma multiforme (GBM) or astrocytoma grade IV
- pilocytic astrocytoma
- pilomyxoid astrocytoma
- pleomorphic xanthoastrocytoma (PXA)
- subependymal giant cell astrocytoma (SEGA)
References
- ↑ WHO International Histological Classification of Tumors. Histological Typing of Tumours of the Central Nervous System. Kleihues et al. Springer-Verlag 2nd ed. 1993
- ↑ Pathology of Tumors of the Nervous System. 5th Ed. DS Russell & LJ Rubinstein, Williams & Wilkins, Baltimore, 1989, pg 95
- ↑ Cotran et al Robbins Pathologic Basis of Disease, W.B. Saunders Co, Philadelphia, PA 1989 pg 1414
- ↑ Harrison's Online, Chapter 370, McGraw-Hill, 2002
- ↑ 5.0 5.1 5.2 Medical Knowledge Self Assessment Program (MKSAP) 16, American College of Physicians, Philadelphia 2012