Neurologic Tumours

1. Neurologic Tumours Part 2

2. 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.

3. 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.

5. 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.

6. 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.

8. 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.

9. 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.

11. Non secreting adenoma. Mass arising at the pituitary stalk and extending superiorly and laterally into the suprasellar cistern.

12. Lateral mass of the pituitary gland. Gadolinium scan shows encasement of both distal internal carotid arteries.

13. T1 weighted coronal MRI view demonstrates a suprasellar macroadenoma of the pituitary in this 37 y.o. man

14. Large pituitary adenoma extending downward into the right cavernous sinus in a 79 year old woman.

16. Microadenoma

17. 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.

18. 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.

19. 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.

21. CT shows a Chordoma as a calcified mass protruding up from the clivus and deforming the brainstem.

23. 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.

25. 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.

26. 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

28. 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.

30. 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.

32. 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.

34. 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.

35. Rim enhancing lesion that contains dense calcification and large cystic component that extends into the posterior fossa. Notice associated hydrocephalus.

36. Craniopharyngioma. Sagittal MRI scan demonstrates large multiloculated suprasellar mass with cystic and lipid components