- Published on
Pathology-Central Nervous System (CNS) Neoplasms
I. Astrocytic Tumors
- Most common primary intracranial neoplasms in adults. Unknown etiology. Typically arise in cerebral hemispheres.
- Presentation: Headaches, seizures, focal neurological signs.
- Histological Spectrum & Grading (WHO): Differentiation dictates grade and prognosis. Higher grade = worse outcome. Key genetic alterations drive progression.
|
Grade |
Tumor Type |
Histological Features |
Genetic Alterations |
Average Survival |
|---|---|---|---|---|
|
II |
Diffuse Astrocytoma |
Slightly increased glial cellularity, mild atypia |
P53 mutation, PDGFR-A overexpression |
~5 years |
|
III |
Anaplastic Astrocytoma |
Increased cellularity, greater atypia, mitotic figures |
RB and P16 mutations added |
~3 years |
|
IV |
Glioblastoma |
Highly aggressive; atypical astrocytes, necrosis, vascular proliferation |
(Above + more aggressive changes) |
<1 year |
II. Oligodendroglial Tumors
- Usually arise in cerebral hemispheres.
- Presentation: Neurological signs or seizures.
- Genetic Alterations: Loss of heterozygosity at chromosomes 1p and 19q is common. Progression to anaplastic histology involves loss of 9p and 10q, and CDKN2A mutations.
|
Grade |
Tumor Type |
Histological Features |
Genetic Alterations |
Average Survival |
|---|---|---|---|---|
|
II |
Oligodendroglioma |
Well-differentiated; round nuclei, clear cytoplasm, calcification common |
1p/19q loss |
~10 years |
|
III |
Anaplastic Oligodendroglioma |
Increased cellularity, atypia, increased mitotic activity |
1p/19q loss, 9p/10q loss, CDKN2A mutations |
2-3 years |
III. Ependymal Tumors
- Originate from ependymal-lined ventricular system.
- Location: Adults – mostly spinal cord; Children – mostly around fourth ventricle.
- Histology: Mostly well-differentiated (WHO grade II); regular round nuclei, fibrillary background, glandular structures, perivascular rosettes.
- Prognosis: Children (posterior fossa) ~50% 5-year survival; Adult spinal tumors have better outcomes.
IV. Meningiomas
- Composed of neoplastic meningothelial cells.
- Location & Appearance: Usually smooth, well-circumscribed, adherent to dura mater; can infiltrate skull.
- Grading (WHO) & Prognosis: Most are low-grade (I), low recurrence risk post-surgical excision.
|
Grade |
Tumor Type |
Histological Features |
Prognosis |
|---|---|---|---|
|
I |
Meningioma |
Low mitotic activity, minimal atypia |
Low recurrence risk post-surgical excision |
|
II |
Atypical Meningioma |
Increased mitotic activity, cytological atypia or necrosis |
Higher recurrence rate; may require radiotherapy |
|
III |
Anaplastic Meningioma |
Markedly atypical cells, very high mitotic activity |
Aggressive, malignant |
V. Medulloblastoma
- Predominantly in children. Primitive embryonal tumor, exclusively in cerebellum.
- Presentation: Rapid growth, hydrocephalus. Can disseminate via CSF.
- Histology: Very cellular; mitotically active small cells, hyperchromatic nuclei, scant cytoplasm.
- Prognosis: Rapid growth; fatal without treatment; ~75% 5-year survival with treatment.
VI. Primary CNS Lymphomas
- Lymphomas arising in CNS without extra-CNS disease.
- Association: Strong association with immunosuppression.
- Most common type: Diffuse large B-cell lymphoma; sheets of large atypical B-lymphoid cells.
VII. CNS Metastases
- Occur at grey-white matter junction.
- Common Primary Cancers: Breast, lung, renal, melanoma.
