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Brain Tumour

Table: Malignant intracranial tumours

 

 

Histological type

Common site

Malignancy

Age

Glioma (Astrocytoma)

Cerebral hemisphere

Cerebellum

 

Brain stem

+ + - + + +

+ - + +

+ + - + + +

+ - + +

Adult

Childhood

Adult

Childhood/Adolescence

Oligodendroglioma

Cerebral hemisphere

+ + - + + +

Adult

Medulloblastoma

Posterior fossa

+ + + - + + + +

Childhood

Ependymoma

Posterior fossa

+ + + - + + + +

Childhood/adolescence

Microglioma (Cerebral lymphoma)

Cerebral hemisphere

+ + - + + +

Adult


Table: Benign intracranial tumours

 

Histological type

Common site

Age

Meningioma

Cortical dura

Parasagittal

Sphenoid ridge

Suprasellar

Olfactory groove

Adult

Neurofibroma

Acoustic neuroma

Adult

Craniopharyngioma

Suprasellar

Childhood/adolescence

Pituitary adenoma

Pituitary fossa

Adult

Colloid cyst

Third ventricle

Any age

 

Important Points: Facts to Remember:

 

The most common tumors in children are: Leukemia

  1. The most common solid tumour in children are: CNS tumors
  2. The most common site of brain tumors in children is Infratentorial (cerebellar)
  3. The most common site of brain tumors in neonates is supratentorial
  4. The most common CNS tumors in children are Glial tumors
  5. Most common posterior fossa tumor in children is astrocytoma.
  6. The most common intracranial neoplasm in adult is astrocytoma.

 

'Most common Primary Intracranial Neoplasms in adults

  1. Astrocytomas (Type of Glioma and includes Glioblastoma Multiforme) ≈30%
  2. Meningiomas   15%

Glial tumors

  1. Astrocytomas
  2. Oligodendroglioma
  3. Ependymomas

Note: Most common glial tumors is astrocytomas.


Cerebellar Astrocytomas

  1. Cerebellar Astrocytomas are equally common in both males & females.
  2. The predominant group of astrocytomas in childhood are low grade astrocytomas (Nelsons)
  3. Juvenile Pilocytic Astrocytoma (JPA) is the most common astrocytoma in children
  4. Juvenile Pilocytic Astrocytoma is a low grade tumor and is classified as a WHO grade I tumor
  5. Cerebellar Astrocytomas (Juvenile JPA) most commonly develop during the first two decades of life (WHO classification of Tumors of CNS)
  6. Cerebellar Astrocytomas have a very good prognosis
  7. With complete surgical resection the overall survival for Juvenile Pilocytic Astrocytomas approaches 80% - 100%

Astrocytomas

  1. Non infiltrating (low grade) Benign: WHO grade I
    1. Pilocytic astrocytoma
    2. Pleomorphic xanthoastrocytoma
    3. Sub ependymal giant cell astrocytoma
  2. Infiltrating WHO Grade II, III, IV
    1. Low grade astrocytomas (WHO Grade II)
      1. Fibrillary              
      2. Protoplasmic        
      3. Gemistocytic
    2. High Grade (WHO Grade III/IV)
      1. Anaplastic Astrocytoma (WHO III)        
      2. Glioblastoma Multiforme (WHO IV)
Important points
  1. Astrocytoma (Cerebellar)
    1. Most common posterior fossa tumor in children is Cerebellar Astrocytoma.
    2. Most common brain tumor in children is also Cerebellar Astrocytoma.
    3. Astrocytoma also has the best prognosis in children.  
    4. Tumor with best prognosis in children is also Astrocytoma.  
  2. Medulloblastoma
    1. The second most common posterior fossa tumor in children.
    2. Tumor which spreads along CSF pathways is medulloblastoma.
    3. Tumor which is capable of metastasizing to extracranial sites is medulloblastoma. (LQ 2012).
    4. Medulloblastoma is highly radiosensitive.
  3. Brain Stem Gliomas:
    1. These are the third most frequent post fossa tumors in children.
  4. Craniopharyngioma:
    1. These are the most common supratentorial tumor in children.


Medulloblastomas

 

Medulloblastomas are highly radiosensitive tumors of the CNS and more radiosensitive than all gliomas (Astrocytoma, Ependymoma, Glioblastoma Multiforme) whereas Glioblastomas are the least radiosensitive'

 

Important Points:
  1. Medulloblastoma is a highly malignant primary brain tumor that originates in the cerebellum or posterior fossa.
  2. Originally considered to be a glioma, medulloblastoma is now known to be of the family of cranial primitive neuroectodermal tumors (PNET).
  3. Medulloblastoma is the most common PNET originating in the brain.
  4. All PNET tumors of the brain are invasive and rapidly growing tumors that, unlike most brain tumors, spread through the  CSF and frequently metastasize to different locations in the brain and spine (bone) (LQ 2012).


Recent Advances: (AIIMS May 2010)

 

Chang classification staging system.

  1. M0 - No gross subarachnoid or hematogenous metastasis
  2. M1 - Microscopic tumor cells found in CSF
  3. M2 - Gross nodular seeding in cerebellum, cerebral subarachnoid space, or in the third or fourth ventricles
  4. M3 - Gross nodular seeding in spinal subarachnoid space
  5. M4 - Extraneuraxial metastasis.


Radiosensitive Brain Tumors in Children

  1. Medulloblastomas and other PNET (Most radiosensitive)
  2. Gliomas (low grade astrocytoma), ependymoma
  3. Pineal blastoma         
  4. Craniopharyngioma
  5. Germ cell tumors (pure germinoma-highly radiosensitive)

Cerebellar hemangioblastoma

Cerebellar hemangioblastoma (LQ 2012) is a benign neoplasm that occurs either sporadically or as part of Von Hippel- Lindau disease (LQ 2012)


Clinically presentation is with:

  1. Cerebellar dysfunction
  2. Hydrocephalus     
  3. Polycythemia (the tumor produces erythropoietin).

Subependymal Giant cell Astrocytomas (SEGCA)

  1. Subependymal Giant cell Astrocytomas are low grade non filtrating (benign) variants of astrocytomas.
  2. They are characteristically but not always associated with tuberous sclerosis
  3. Occur most frequently in patients with autosomal dominant phakomatosis tuberous sclerosis
  4. The most common site of SEGCA is the ependymal wall of lateral ventricle near the foramen of munro   and these tumors tend to grow towards the foramen of munro (leading to obstructive hydrocephalus)
  5. Pathologically lesions are composed of Giant cells
  6. Candle dripping radiographic appearance is characteristic
  7. These tumors predominantly occur is children (lst decade)
  8. These tumors are essentially benign
  9. Total Gross resection is the treatment of choice

Fig: Cerebral tumour of the medial part of the temporal lobe causing distortion of midbrain & third nerve.

 

 

Fig: Downward displacement of the cerebellar tonsils below the level of the foramen magnum. The shaded area represents the position of the cerebellum that is displaced.

 


 

Recent Advances:

 
Chemotherapy for brain Tumour
  1. Carmustine (CCNS) lomustine (BCNS)
  2. Temozolomide: Its main indication is anaplastic astrocytoma which is refractory to conventional treatment. (H- Pg 2604).
  3. Efaproxiral results in a shift of the hemoglobin oxygen dissociation curve to the right. Therefore, oxygen is more readily    released from hemoglobin into tissues. Efaproxiral has significant survival benefit when used as a radiation enhancer in patients with brain metastases originating from breast cancer. It is new drug. It is not given in Harrison’s 17th Edition.

 

Hereditary Syndromes Associated with Brain Tumors (Ref. Hari. 18th ed., Pg- 3384, table 379.2)

Syndrome

Nervous System Neoplasms

Neurofibromatosis type 1 (von Recklinghausen's Disease)

Neuroma, schwannoma, meningioma, optic glioma

Neurofibromatosis type 2

Schwannoma, glioma, ependymoma, meningioma

Tuberous sclerosis

Astrocytoma

von Hippel-Lindau

Hemangioblastoma of retina, cerebellum and spinal cord; pheochromocytoma

Li-Fraumeni

Malignant glioma

Retinoblastoma

Retinoblastoma, pineoblastoma, malignant glioma

Turcot

Medulloblastoma, malignant glioma

Gorlin (basal cell nevus syndrome)

Medulloblastoma

Multiple endocrine neoplasia 1 (Werner syndrome)

Pituitary adenoma, malignant schwannoma





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