Flashcards in W2 - Primary Neoplasms of the CNS - condensed Deck (12):
In which age groups are primary CNS tumours most common?
- 1st decade (0-10yo)
- 5th-6th decades (40-60yo)
Which primary CNS tumours are common in adults?
Which primary CNS tumours are common in children?
- 70% located supratentorial
- Glioblastoma multiforme (6th most common tumour in adults)
- 70% of CNS tumours in CNS arise in posterior fossa (cerebellar lesions common)
- Most of these are astrocytomas (45%) or neuroectodermal neoplasms (45%)
How are primary CNS tumours classified?
May be classified:
Based on cell of origin (histogenetic classification)
- Neural tube (glioma, astrocytoma, oligodendroglioma)
- Neural crest (schwannoma, neurofibroma, meningioma)
- Embryonic remnants (melanoma, germinoma)
Benign vs malignant (rate of growth)
Primary or secondary
How are astrocytomas classified?
Astrocytomas are derived from astrocytes. Most common primary CNS neoplasms.
- Grade I - Well differentiated (low grade)
- Grade II & III - Anaplastic
- Grade IV - Highly undifferentiated (high grade)
Write brief notes on "Glioblastoma multiforme"
- Most common type of astrocytoma
- Classification: Grade IV (high grade) neoplasm = rapid growth, infiltrative, tumour cells show little/no differentiation
- Location: Midline of brain, form "butterfly tumour"
- Neovascularisation common
- Necrosis and haemorrhage common
Write brief notes on "oligodendroglioma"
- Derived from oligodendroglia, but pure oligodendrogliomas rare (usually mixed tumour)
- Rare in children, 3% primary CNS neoplasms in adults
- Location: Cerebral hemispheres
- Classification: Less malignant than astrocytomas (slower growing)
- Can be identified by speckled calcification on X-Ray
Define the following terms:
a) Choroid plexus papilloma
a) Choroid plexus papilloma
A rare, benign tumour derived from ependymal cells that commonly affects the lateral ventricles.
Primary, malignant CNS neoplasm derived from neurons that commonly affects children and are usually found in the midline cerebellar vermis.
Write brief notes on the following primary CNS neoplasms which are derived from cells originating in the neural crest:
- Origin: Arachnoid cap cells (of arachnoid villi)
- Frequency: 18% of intracranial neoplasms in adults (2:1 female/male ratio)
Common sites: Foramen magnum, olfactory groove and wing of sphenoid
- Biological behaviour: Usually benign, often infiltrates adjacent bone and dura
- Origin: Schwann cells (in myelin sheath of cranial & spinal nerves).
- Frequency: 10-12% of primary CNS neoplasms in adults (more common in females)
- Site: Vestibular branch of CN VIII near cerebellopontine angle
- Biological behaviour: Benign (slow growing), well encapsulated.
Briefly define the following terms:
Note: Neurofibromas and craniopharyngiomas are not neoplasms.
A benign tumour arising from the myelin sheath of spinal nerves that is composed of Schwann cells and fibroblasts that are usually found on the dorsal roots of spinal nerves.
A benign, well encapsulated tumour derived from ectodermal cells of Rathke's pouch that is common in children and is usually located in the suprasellar region.
a) Define the term "neurofibromatosis".
b) Is it a common disease?
a) A pair of autosomal dominant disorders with a strong familial pattern of distribution, characterised by lesions in the skin, NS, bones, endocrine glands and viscera.
b) 1/3000-4000 (fairly common)
List and describe the clinical manifestations of Type I (Peripheral) neurofibromatosis
- Café-au-lait spots - Brown, freckle-like spots found in axilla (Crowe's sign) and other intertriginous areas (groin, under breasts, knee and elbow creases) that appear at or shortly after birth.
- Soft, brown/purple mole-like papules found in the dermis that are tender and invaginate into the skin when pressed (button sign).
- Neurofibromas - Firm, discrete nodules attached to a nerve
- Plexiform - An overgrowth of subcutaneous tissues, bone, skin, neurovascular fibromatous tissue
- Neurofibromas in dorsal roots of spinal & cranial nerves
- Scoliosis, bone cysts, cranial bone defects, bone hypertrophy and pathological bone fracture
- Glial tumours of CNS --> Intellectual impairment, hyperactivity, seizures
- Precocious (early onset) puberty
- Lisch nodule (Small, whitish spot on iris of eye)