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CNS Tumors

  1. Annual incidence: 10-17/100,000 persons for India- Cranial tumors.
    1. : 1-2/100,000 persons for intra-spinal tumors.
    2. (50%-primary, rest - metastasis)
  2. 70% of childhood CNS tumors →  in posterior fossa
  3. In children: most common in cerebral hemispheres.
Major classes of brain tumors: Q
  1. Astrocytomas                                        
  2. Oligodendrogliomas                                    
  3. Ependymoma                               
  4. Gliomas                                                  
  5. Neuronal tumors                                        
  6. Poorly differentiated neoplasm
  7. Meningioma
  1. 80% of adult primary brain tumors Q
  2. more common in Cerebral hemispheres, also in cerebellum, brain stem, or spinal cord
  3. 4th - 6th decade
  1. Diffuse fibrillary astrocytoma: ↑ in number of glial cells, transition between neoplastic & normal indistinctQ
  2. Anaplastic astrocytoma - More densely cellular, more pleomorphism, mitotically active cells, some vascular endothelial proliferation Q
  3. Glioblastoma multiforme - additional features of necrosis and vascular or endothelia cell Q proliferation - bulge into lumen: called glomeruloid body, (proliferation by VEGF) & pseudopalisading
  4. Gliomatosis cerebri: affecting multiple regions of brain
  5. Gemistocytic Astrocytoma: Q
    Neoplastic astrocyte has brightly eosinophilic cell body from which emanate abundant stout processes.
  6. Clinically:­Q
  1. Tendency to become more anaplastic with time. 1/3 of glioblastoma have p53 maitation → sec. glioblastoma.
Mean survival:
Well diff. → 5 years
Glioblastoma → 8-10 months
Pilocytic Astrocytoma:
  1. Children & young adults
  2. Cerebellum also floor & wall of III ventricle optic nerves, occasionally cerebral hemisphere.
  3. Relatively benign behavior grow slowly
  1. mural nodule in wall of the cyst.
  2. L/M: cells are bipolar, have long trim hair like processes that are GFAP positive Rosenthal fibres & micro cysts are present.
Pleomorphic Xantho Astrocytoma
Occurs Superficially in temporal lobe of children & young adults.
Brain stem gliomas: Q
  1. occur moistly in 1st two decades of life
  2. compose about 20% of primary brain tumors in this age group
  1. 4th - 5th decade
  2. 5-15 % of gliomas
  3. Mainly in cerebral hemispheres with a predication for white matter.
Gross: Well-circumscribed, gelatinous, gray masses often with cysts, hemorrhage & calcification.

  1. Sheets of regular cells, spherical nuclei, surrounded by clear halo of cytoplasm
  2. Delicate network of anastomiosing capillaries
  3. Calcification is present in 90% of these tumors.
Clin: Q
  1. Better Prognosis than astrocytomas
  2. Anaplastic oligodendrogliomas - Bad Prognosis
Mixed glioma: Q
Neoplasm consisting of oligo dendro glioma & astrocytoma (or less often, others gliomatous comp.)
Ependymoma: Q
→ Location:
In 1st week two decades: IV ventricle (5-10% of prim, brain tumor in this age gp.)
Adult → Spinal cord.
Gross: In IV ventricle: solid or papillary masses extending from the floor of the ventricle
  1. Cells, with regular, round to oval nuclei, abundant granular chromatin
  2. Dense, fibrillary background
  3. Gland like canals, rosettes, tubules
  4. Perivascular pseudorosettes → & true rosettes.
Clinically: Q
Posterior fossa ependymomas manifest with hydro cephalous, sec. to obstr. of IV Ventricle.
  1. CSF dissemination positive
  2. Average survival: 4 year, Prognosis poor. (After surgery & RT)
Myxopapillary ependymomas:
  1. In filum terminate of spinal cord
  2. Contains papillary elements in myxoid background Prognosis depends on completeness of resection
  1. Solid, sometimes calcified slow growing nodules, attached to ventricular lining & protruding into the ventricle.
  2. Usually a symptomatic
  3. May cause hydrocephalous
  4. Most often in lateral & fourth ventricles.
Choroid Plexus Papillomas: Q
  1. Most common in children → commonly in lateral ventricles.
  2. In adult → more often found in IV ventricle
  3. Papillae have connective tissue stalk covered with cuboidal or columnar epithelium.
  4. Present with hydrocephalus:
    due to obstruction
    due to overproduction of CSF
Colloid Cyst of the III ventricle Q
  1. Most often in young adults
  2. Attached to roof of III ventricle, can obstruct one or both foramina of Monro.
    Cyst has thin fibrous capsule, lining of low to flat cuboidal epithelium, contains gelatinous proteinaceous material .
Neuronal Tumors
  1. Gangliocytomas:
  1. Myelin appearing neurons (ganglion cells) constituting entire population of the lesion
  2. Usually found in floor of III ventricle, hypothalamus or temporal lobe
Grossly: well circumscribed masses, with focal calcifications, small cysts
  1. Ganglion cells, admixed with glial neoplasm.
  2. Gross: Similar to glioma of comparable grade
Most commonly in temporal lobes
IHC for neuronal component: Neuronal proteins, neurofilaments and synaptophysin

Cerebral Neuroblastomas: Rare
Occurs in cerebellar hemispheres of children
Highly aggressive clinical behavior
Composed of small undifferentiated cells with characteristic Homes Wright rosettes
Central Neurocytomas: Q
  1. Found within and adjacent to ventricular system
  2. Evenly spaced, round uniform nuclei (similar to oligodendrogliomas)
  3. Ultra structure and IHC reveals neuronal lineage
Dys embryoplastic neuroepithelial tumors (DNET):
  1. Non anaplastic tumor of childhood
  2. Mixed glial- neuronal tumor, characterized by intra - cortical location, cystic change, frequent association with dysplastic cortex, nodular growth and presence of well differentiated floating neurons in pool of mucopolysaccharides rich fluids and surrounding neoplastic glia without anaplastic features.
Poorly Differentiated Neoplasms:
  • Most common is medulloblastoma → accounts for 20% of brain tumors in children Q
  1. Affects children Q
  2. Cerebellum (in children: midline cerebellum) Q
  3. Gross: Well circumscribed, gray, friable, extending to surface of cerebellar fossa
  4. L/M:  Extremely cellular, sheets of anaplastic cells
  5. Cells: Small, scant cytoplasm, hyperchromatic nuclei, mitoses +
  6. Tumor has potential to express neuronal (Homer Wright rosettes, or neurosceretory granules) and glial (GFAP) phenotype.
  7. Tumor cell aggregate beneath pia, extend into subarachnoid space, disseminate through CSF (to cauda equina → "drop. metastases) Q
  1. Highly malignant
  2. Dismal prognosis for untreated patients
  3. Radio sensitive tumor Q
  4. Ass. with i (17 q)
  5. With total excision & RT, (5 year survival rate - 75%)
  1. Derived from vestigial remnants of Rathke pouch Q
  2. Slow growing, seen in childhood Q
  3. 3-4 cm, cystic with calcification two forms
  1. Adamantinomatous
  2. Papillary
Other Tumors: Q
  1. Primary Brain Lymphoma:
  1. Accounts for 2% of extra - nodal lymphomas, & 1 % of intracranial, tumors
  2. Most common CNS neoplasm in immunosuppressed patients (In non-immunosuppressed, frequency ↑ after 60 years)
  1. Primary CNS Lymphoma
  1. Multiple tumor masses
  2. Within Brain parenchyma
  3. Nodal, B/M or extranodal involvement outside CNS is rare & late complication.
→ NHL arising outside CNS rarely involves brain parenchyma
- Involvement manifested by malignant cells within CSF & around intradural nerve roots, occ. by infiltration of superficial aspects of cerebrum or spinal cord
The major classes of Primary Brain Tumors include:
A. Gliomas e.g. astrocytoma; Oligodendroglioma; Ependymoma, etc.
B. Neuronal tumors e.g. Ganglioglioma, Gangliocytoma, DNET, Central neurocytoma, etc.
C. Poorly differentiated tumors e.g. Medulloblastoma, Rhabdoid tumor, etc.
D. Miscellanous tumors e.g. Primary CNS lymphoma, etc.

- Pure neuronal lesion = spinocerebellar ataxia.Aiims 2006,2011

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