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A solid tumor of
the CNS characterized usually by increased intracranial pressure and/or
focal neurologic signs.
Incidence is
3.3/100,000. It is the most common solid tumor of childhood, the 2nd
most common form of childhood CA (20%), and the 2nd most common cause of
childhood cancer related deaths (< 15 yrs of age). Median age at time of
diagnosis is 5 years. Risk factors include neurocutaneous syndromes,
immune dysfunction, AIDS, ataxia telangiectasia, non-Hodgkin's Lymphoma,
environmental factors (parental exposure to organic carcinogens,
radiation exposure in utero, and therapeutic radiation for tinea capitis
or primary cancer), and familial (chromosomal abnormalities).
Pathogenesis
includes two distinct histiologic groups:
1.
Primitive Neuroectodermal Tissue (PNET)
a.
Represent primitive undifferentiated cells
b.
Involve the cerebrum, pineal gland (pineoblastoma),
cerebellum (medulloblastoma), spinal cord
2.
Glial Tissue
a.
Most CNS tumors arise from glial tissue
b.
This supporting tissue is ectodermal in origin
c.
3 types:
i. Astrocytes
1. Star-like cells arising from
astroblasts
2. Give rise to astrocytomas
3. Cerebrum, corpus callosum, optic
chiasm & nerve, cerebellum, brain stem,
around 3rd ventricle
ii. Ependymal Cells
1. Give rise to ependymomas
2. Cerebrum, ventricles,
cerebellopontine angle
iii. Oligodendrocytes
1. Tree-like cells arising from
oligodendroblasts which give rise to an
oligodendroglioma
2. Cerebrum, corpus callosum, around 3rd
ventricle
Clinically
there are two distinct patterns of presentation:
1.
Infratentorial (posterior fossa tumors)
i. Obstructive Hydrocephalus with elevated ICP
with diplopia, headache, papilledema, vomiting
ii. Cerebellar Signs
1. vermis - truncal ataxia enhanced with
sit/standing
2. lateral - ipsilateral extremity
ataxia, dysdiadocho-kinesia
3. anterior - broad-based gait
4. visual - nystagmus, obscuration of
vision, head tilting & nuchal rigidity
iii. Coning (hydrocephalus, Cushing's Reflex,
coma)
2.
Supratentorial
a.
Focal Neurologic Signs (hemiparesis, complex partial
seizures)
b.
Personality Changes
c.
Metastases primarily effect the leptomeningeal area -
pia mater + arachnoid, spinal column, and extracranial –
bone.
Investigations
include imaging studies such as, MRI (best for posterior fossa tumors),
CT (non-enhanced and enhanced), and contrast myelography (for spinal
mets).
Pathologic studies of the tumor and bone marrow
should be performed, as well as serum studies (TSH,
ACTH, LH, FSH, GH, ADH, prolactin) and CSF
studies (germ cell - bHCG, alpha-fetoprotein,
medulloblastoma - monoclonal antibodies,
polyamine cytology - tumor cells)
Management
involves surgery, radiation, and chemotherapy depending on the grading
and staging of the tumor, as is prognosis
This edited version is
being used with the permission of its original author, Dr.
Alan Gandy. |