CNS tumours Flashcards
Most common brain tumour
Is secondaries or metastasis
(commonly from small cell carcinoma of lung)
Most common 1° CNS tumour- glioma (or meningioma)
Most common brain tumour in children
Pilocytic astrocytoma
Most common malignancy of brain in children
Medulloblastoma
Classification of CNS tumours
1. Glial tumours: •Astrocytoma •Oligodendroglioma •Ependymoma 2. Undifferentiated tumours: •Medulloblastoma 3. Meningial tumour: •Meningioma 4. Others: •Lymphoma •Germ cell tumour
Anne Mayo Grading system of CNS tumours
A. Atypia M. Mitosis E. Endothelial proliferation N. Necrosis 4 grades based on these factors: 1. None 2. Atypia 3. Atypia and mitosis 4. All 4 Similar to WHO system
Astrocytoma
4 Classes
4 classes: 1. Pilocytic 2. Diffused fibrillary 3. Anaplastic 4. GBM glioblastoma multiformi Prognosis worsens as we move down the classes
Pilocytic astrocytoma
In children
Benign
Most common 1° benign tumour of children
Seen in cerebellum, floor of 4th ventricle
Tumours showing mural nodules
- Pilocytic astrocytoma
2. Pleomorphic xanthoastrocytoma
Features of pilocytic astrocytoma
Gross: 1. Cysts 2. Mural nodules Histo: 1. Microcysts 2. Rosenthal fibres 3. Eosinophilic granular bodies (EGB)
Glioblastoma multiformi
WHO grade 4 type of astrocytoma
Poor prognosis
In elderly
Butterfly tumour (crosses the midline)
Features of glioblastoma multiformi
Microscopy:
1. Nuclear pleomorphism
2. High cellularity
3. High mitosis
Endothelial vascular proliferation with glomeruloid bodies
Serpentine geographical necrosis surrounded by pseudopalisading tumour cells
Schiller Duval bodies
Glomeruloid bodies are also seen (in addition to glomeruloblastoma multiformi) in yolk sac tumours and are called Schiller Duval bodies
IDH wild type of glioblastoma
•Primary glioblastoma consisting 90% of cases •Supratentorial •Age of presentation: 55 years •Extensive necrosis and poor necrosis Mutations: 1. TERT 2. EGFR 3. PTEN
IDH mutant type of glioblastoma
•Secondary glioblastoma consisting 10% of cases • Infratentorial • Age of presentation: 45 years • Mild necrosis and better prognosis Mutations: p53
Oligodendroglioma
WHO grade II
Age: middle-elderly
Usually affects cerebral cortex
Genetics:
1. 90% cases are due to mutations of IDH1 and IDH2 genes
2. Loss of 1p and 19q ➡️ highly chemosensitive
Oligodendroglioma microscopic features
- Cells with perinuclear halo: fried egg appearance
- Calcifications
- Anastomosing vascular channels: chicken wire blood vessels
- Movement of tumour cells around nerve fingers: perineuronal satellitosis
Fried egg appearance is seen in
- Hairy cell leukaemia
2. Oligodendroglioma
Calcifications are shown by following tumours
.
C. Craniopharyngioma
O. Oligodendroglioma
M. Meningioma
Ependymoma
From ependymal lining Associated with NF-2 gene mutations Most common site in adults: spinal cord CSF dissemination is common Microscopy- perivascular pseudorosettes: Tumour cells surrounding a blood vessel
Medulloblastoma
Undifferentiated tumour ➡️ poor prognosis
Most common 1° malignant brain tumour in children
Drops in CSF ➡️ ‘drop metastasis’
Usually occurs in children in the posterior fossa/ cerebellum
Highly radiosensitive
Microscopy of medulloblastoma
Sheets of small round blue cells with scanty cytoplasm
Homer Wright rosettes
Meningioma
Benign tumour of adults
Usually due to NF-2 gene mutations
Progesterone responsive ➡️ increased in pregnancy
Previous radiation exposure is a risk factor
Microscopy of meningioma
5 types: F. Fibroblastic P. Psammomatous S. Spindle cell S. Secretory T. Transitional
Psammoma bodies
Foci of dystrophic calcifications seen in: M. Meningioma P. Papillary carcinoma of thyroid P. Papillary renal cell carcinoma P. Prolactinoma S. Serous cystadenocarcinoma of ovary
Types of meningioma
1. Atypical meningioma: Clear cell, or Choroid 2. Anaplastic meningioma Rhabdoid or Papillary >20 mitosis/HPF
Atypical meningioma characteristics
4 or more mitosis/10 HPF Or At least 3 of the following 1. Increased cellularity 2. Prominent nucleoli 3. High nucleocytoplasmic ratio 4. Necrosis 5. Patternless growth
Schwanomma
Usually due to NF-2 gene missions on chromosome 22 (merlin)
Arises from inferior vestibulocochlear nerve (VIII)
Well circumscribed encapsulated tumour
Microscopy of Schwanomma
Microscopy:
- Antoni A - hypercellular area
- Antoni B - hypocellular area
- Verocay bodies - empty spaces in between the above 2
Neurofibromas
Benign tumour
Mutations in NF-1 gene on chromosome 17 (neurofibromin)
Non encapsulated tumour
GFAP (glial fibrillary acidic proteins) positive brain tumours
Astrocytoma Oligodendroglioma Ependymoma Medulloblastoma Choroid plexus tumours
Tuberous sclerosis
Autosomal dominant Caused by mutations in: TSC 1 - Hamartin TSC 2 - Tuberin Clinically: 1. Seizures 2. Mental retardation 3. Adenoma sebaceum (angiofibroma of nose) Increased risk of developing other tumours
Tuberous sclerosis increases risk of developing tumours like
- Heart - Rhabdomyomas
- CNS:
• Subependymal nodules
• SEGA (subependymal giant cell astrocytoma)
• Cortical tubers - Kidney - Renal angiomyolipoma
- Skin:
• Ash Leaf macules
• Shagreen’s patch - Lungs - Lymphangioleiomyomatosis
Von Hippel Lindau disease (VHL)
Autosomal dominant Gene on chromosome 3p In kidney- clear cell renal carcinoma CNS- cerebellar hemangioblastoma Pancreas- cysts Adrenals- pheochromocytoma Skin- epidermal cysts
