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MEDULLOBLASTOMAS AND NEURONAL TUMOURS

MEDULLOBLASTOMAS AND NEURONAL TUMOURS

What category do medulloblastomas fall under? 

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Medulloblastomas fall under the category of poorly differentiated neoplasms: with this particular type of brain tumour, it is difficult for a pathologist (histopathologist) to find any cells that resemble mature brain cells. It is most common within children, where it accounts for approximately one fifth of paediatric brain tumours.

What is the prognosis for those with medulloblastoma? 

The tumours are malignant in nature, and therefore the prognosis is dismal for those left untreated. However, the situation improves massively if the tumours are treated by means of a combined attack of chemotherapy and surgery as the cells are very sensitive to radiation. Approximately three quarters of patients that are treated manage to survive for approximately 5 years.

Where are medulloblastomas located within the brain? 

Medulloblastomas are chiefly located within the cerebellum, but they may also be found elsewhere in the nervous system. In children, the tumours are often seen in the midline of the cerebellum, but in adults, the tumours have a tendency to grow more laterally (towards the sides). Outside of the cerebellum, medulloblastomas are referred to by a different name: they are known as CNS-PNETs or central nervous system primitive neuroectodermal tumours.

What do medulloblastomas look like, both macroscopically and

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microscopically? 

They appear grey and extremely cellular in nature and there may be ‘small blue’ anaplastic sheets of cells when you look with the naked eye. Under the microscope, the individual cells have little cytoplasm (i.e. the nucleus encompasses most of the cell) and the nuclei are darkly shaded when stained and small in size. The cells also are not very consistent shape-wise: they are highly anaplastic in nature.

 

 

 

What are the types of neuronal tumours? 

Pic: https://www.ucdmc.ucdavis.edu/cancer/images/body/cancer_types/neuronal-cancer-cell.jpg

There are three chief types of neuronal tumours: central neurocytomas, gangliogliomas and dysembroyplastic neuroepthelial tumours. They are all considered as low-grade tumours.

 

Central Neurocytoma 

These tumours are located both within the ventricular system (the lateral or third ventricles) and under the microscope, there are islands of neutrophils and the cells are round, uniform and are evenly spaced apart.

Gangliogliomas 

Gangliogliomas are typically slow-growing tumours until they hit the anaplastic stage: when they become anaplastic, they are relatively aggressive. A characteristic symptom associated with gangliogliomas is seizures. Under the microscope, they look like a mixture of normal mature cells and low-grade astrocytomas.

Dysembryoplastic neuroepithelial tumour 

Pic: http://www.jcytol.org/articles/2011/28/4/images/JCytol_2011_28_4_147_86339_f6.jpg

These tumours often present in childhood and like gangliogliomas, the patients with these tumours have seizures. They typically grow within the upper layers of the temporal lobe and under the microscope, they have neurons arranged in columns and small round cells. The prognosis of patients that are diagnosed and treated for this tumour is good.