Neurologic Tumours

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Neurologic Tumours

• Part 2

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Choroid Plexus Papilloma

• Most commonly encountered during the first decade
  of life.
• This usually arises in the lateral ventricles.
• Hydrocephalus occurs secondary, with the
  overproduction of CSF
• CT shows a homogenous, lobulated, isodense or
  hyperdense intraventricular mass.

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Choroid plexus papilloma of the third ventricle.
Shows a lobulated mass in the third ventricle
extending into the right frontal horn. The mass
is isointense to the surrounding CSF. The lesion
obstructs the third ventricle and produces
hydrocephalus.
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Pituitary Adenoma

• 12-18 of all intracranial neoplasms.
• These are usually benign tumours and have a high
  rate of cure with surgery and irradiation.
• They are usually well encapsulated
• Symptoms usually present as the result of
  pressure on adjacent tissue due to the presence
  of the lesion.

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Pituitary Adenoma

• Vision defects, headaches, seizures and erosion
  render the sella turcica asymmetric and can best
  be seen as a ballooning enlargement on the
  lateral view of the skull.

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Pituitary Adenoma

• Classified whether or not the tumour is
  endocrinogically active.
• Because endocrinogically active tumours are
  symptomatic, they tend to present clinically at a
  much smaller size than non-secreting tumours.
  Acromegaly etc.
• The later may cause symptoms by compression of
  adjacent cerebral nerves.

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Pituitary Adenomas

• Tumours smaller than 1 cm are termed
  microadenomas, and show decreased enhancement on
  both CT and MRI compared to the rest of the
  gland.
• Macroadenomas often extend into the supracellar
  cistern and compress the optic chiasm.
• Pituitary tumours may encase the adjacent carotid
  arteries and also extend into the cavernous
  sinuses.

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Non secreting adenoma. Mass arising at the
pituitary stalk and extending superiorly and
laterally into the suprasellar cistern.
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Lateral mass of the pituitary gland. Gadolinium
scan shows encasement of both distal internal
carotid arteries.
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T1 weighted coronal MRI view demonstrates a
suprasellar macroadenoma of the pituitary in this
37 y.o. man
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Large pituitary adenoma extending downward into
the right cavernous sinus in a 79 year old woman.
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Microadenoma
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Chordoma

• Chordomas are tumours that arise from remnants of
  the notochord (embryonic neural tube).
• Although any part of the vertebral column and
  base of the skull can be involved.
• The tumours are locally invasive but do not
  metastasize.

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Chordoma

• Chordomas arising at the base of the skull
  produce the striking clinical picture of multiple
  cranial nerve palsies on one or both sides
  combined with a retropharyngeal mass and erosion
  of the clivus.
• On plain films, a chordoma tends to be a bulky
  mass causing ill-defined bone destruction or
  cortical expansion.

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Chordoma

• On CT scans , chordomas at the base of the skull
  tend to appear as lesions that are slightly
  denser than brain tissue and often demonstrate
  contrast enhancement.
• On MRI sagittal scans well demonstrate the clival
  origin of the mass and its effect on surrounding
  structures.

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CT shows a Chordoma as a calcified mass
protruding up from the clivus and deforming the
brainstem.
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Clival Chordoma. Sagittal Mri shows a low
intensity multi lobulated mass deforming and
displacing the brainstem, destroying the clivus,
and extending into the sella turcica and
nasopharynx.
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Acoustic Neuroma

• Acoustic Neuromas usually occur in the middle
  aged and elderly.
• They are firm encapsulated tumours which vary
  greatly in size at presentation.
• The larger tumours may become irregular and
  lobulated and can become cystic.
• As a rule they are single solitary tumours.

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Acoustic Neuroma

• Large and medium sized acoustic tumours are
  generally isodense and difficult to visualise on
  the unenhanced scan.
• Rotational deformity of the fourth ventricle
  however may suggest their presence as may
  symmetrical hydrocephalus.
• Most will show clearly after contrast

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Acoustic Neuroma

• MRI shows acoustic neuromas very well with or
  without gadolinium.
• Direct coronal cuts can image both sides at the
  same time and since there is no interference from
  bone, even small tumours can be identified in the
  meatus or extending into it.

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Primitive Neuroectodermal Tumour

• This actually refers to a group of paediatric
  brain tumours.
• Most common type is the cerebellar
  medulloblastoma. Another type if the cerebral
  neuroblastoma, which develops during the first
  years of life. Like medulloblastomas, they
  typically have dense cellularity and may be
  hyperdense on unenhanced CT scans.

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Pineal Germinomas

• Most common type of solid pineal gland tumour
• When these lesions are large, they may compress
  the midbrain and produce paralysis of upward
  gaze.
• These tumours are usually developmental
• More commonly occur in males under 35 y.o.

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Craniopharyngioma

• Benign tumour that contains both cystic and solid
  components.
• The lesion usually originates above the sella
  turcica, depressing the optic chiasm and
  extending up into the third ventricle.
• Most craniopharyngiomas have calcification that
  can be detected on plain skull films or CT scans.

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Rim enhancing lesion that contains dense
calcification and large cystic component that
extends into the posterior fossa. Notice
associated hydrocephalus.
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Craniopharyngioma. Sagittal MRI scan
demonstrates large multiloculated suprasellar
mass with cystic and lipid components