These two tumour types comprise approximately one quarter of all gliomas with astrocytomas taking up the other three quarters.
What is the prognosis of patients with oligodendrogliomas?
Oligodendrogliomas tend to be diagnosed more often than ependemyomas. The prognosis of patients with oliogodendrogliomas is better overall than that of patients with astrocytomas, however it worsens if the tumour progresses to the anaplastic stage. The evolution of oligodendrogliomas is similar to that of astrocytomas. If the tumour is caught in time, and treated, via means of surgery, the patient may be able to live up to ten years, and have a median survival rate of 5 years.
What do oligodendrogliomas appear like on the macroscopic and microscopic level?
On the macroscopic (naked eye) level, as the picture above shows, oligodendrogliomas appear like grey masses that are jelly-like in consistency and may also appear cystic. If the tumour becomes a higher grade, there may be signs of necrosis (dead tissue). Under the microscope, as the picture alongside shows, they are made of sheets of regular cells encased with a delicate network of capillaries. Other features that may be present include calcification and haemorrhaging (bleeding).
Ependymomas are quite uncommon: they tend to reside next to the ventricular system, and more often than not they end up within the spinal cord. They often present within people of less than thirty years of age: in teenagers, the tumour is often located within the fourth ventricle, but for adults who are diagnosed, the tumour has moved down the central canal of the spinal cord.
What do ependemyomas appear like under the microscope?
If the tumour is located within the fourth ventricle, they are relatively solid, with cells that show regular, round to oval nuclei and there are fibres within the background. A characteristic feature to look out for when confirming these types of tumours, as the picture alongside shows, is the presence of true rosettes: they are also known as tubular formations. If the tumour becomes anaplastic in nature, the volume of cells becomes more dense, and there is necrosis present.