**3. Etiology and pathogenesis**

Development of brain tumours occurs as a consequence of cellular genetic alterations that allow them to evade normal regulatory mechanisms and destruction by the immune system. These changes may be caused by an inherited or acquired (chemical, physical or biological neuro-carcinogens) cause. Overall, only a very small percentage of brain tumors can be ascribed to the effect of inherited inclination (**Table 2**). The different environmental factors involved and alleged typically involve ionizing radiation, non-ionizing radiation, N-nitroso compounds, viral infections (JC virus, cytomegalovirus, HIV, SV-40, varicella-zoster, chicken pox) and head injury [6].

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*An Overview of Pediatric CNS Malignancies DOI: http://dx.doi.org/10.5772/intechopen.88189*

**locus**

16p13

**Gene Type of CNS tumour**

NF type 1 17q11 NF1 Neurofibroma, meningioma, optic nerve glioma

TSc1/TSC2 SEGA

NF2 22q12 NF2 Meningioma, schwannoma

VHL 3p35 VHL Haemangioblastoma

Li-Fraumani 17q13 p53 Glioma Gorlin's syndrome 9q31 PNET

**Syndrome Gene** 

TS 9q34,

**4. Pathology and classification**

• subependymal giant cell astrocytoma

**Astrocytic tumors**

*CNS tumour along with gene involved.*

**Table 2.**

• pilocytic astrocytoma

• diffuse astrocytoma

• anaplastic astrocytoma

• giant cell glioblastoma

**Oligodendroglial tumors**

• anaplastic oligodendroglioma

• anaplastic oligoastrocytoma

**Oligoastrocytic tumors**

• oligoastrocytoma

**Ependymal tumors**

• subependymoma

• oligodendroglioma

• glioblastoma

• gliosarcoma

• Pilomyxoid astrocytoma

• pleomorphic xanthoastrocytoma

## *An Overview of Pediatric CNS Malignancies DOI: http://dx.doi.org/10.5772/intechopen.88189*


#### **Table 2.**

*Current Cancer Treatment*

histological subtypes of CNS tumours are recognized but their incidence varies with age. Incidence in Africa is around 11 per 10,00,000 and in Japan and Europe it ranges from 20 to 30 per 1,000,000. The male to female ratio is 1.25:1, as slightly higher frequency of medulloblastoma and CNS germinoma is seen in boys [4]. The most common histological subtypes along with location are mentioned below

**Location Tumor type Relative frequency (%)** 

Fibrillary astrocytoma 5 Ganglioganglioma 2.5

ATRT 1.3 Pilocytic astrocytoma 23.5 Ependymoma 3.8 Brainstem glioma 10–20

Pineal parenchymal tumour 1.9

Optic hypothalamic glioma 3–6

Dysembryoplastic neuroepithelial tumor 0.6 Desmoplastic infantile ganglioglioma 0.6 Choroid plexus papilloma 0.9 Ependymoma 3.8 Anaplastic ependymoma 3.8 Anaplastic astrocytoma 7.2 Glioblastoma 7.2 Supratentorial PNET 1.9 Choroid plexus carcinoma 0.6

Supratentorial Pilocytic astrocytoma 23.5

Posterior fossa Medulloblastoma 16.3

Pineal tumours Germ cell tumour 2.5

Suprasellar Craniopharyngioma 5.6

**in 0–17 years old**

Development of brain tumours occurs as a consequence of cellular genetic alterations that allow them to evade normal regulatory mechanisms and destruction by the immune system. These changes may be caused by an inherited or acquired (chemical, physical or biological neuro-carcinogens) cause. Overall, only a very small percentage of brain tumors can be ascribed to the effect of inherited inclination (**Table 2**). The different environmental factors involved and alleged typically involve ionizing radiation, non-ionizing radiation, N-nitroso compounds, viral infections (JC virus, cytomegalovirus, HIV, SV-40, varicella-zoster, chicken pox)

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and head injury [6].

(**Table 1**).

**Table 1.**

**3. Etiology and pathogenesis**

*Common brain tumor types with location and frequency [5].*

*CNS tumour along with gene involved.*
