A haemangioblastoma tumour is formed from cells that line the blood vessels, at an early stage of their development.
It is almost always a benign tumour, which may be like a cyst (a fluid-filled area), and more than one tumour may be present.
Haemangioblastomas are usually found in the cerebellum, at the back of the brain. They are commonly slow-growing tumours and do not spread to other parts of the brain.
Haemangioblastomas can be found in adults and children, and mostly occur as part of a rare hereditary condition known as von Hippel-Lindau disease (VHL). Only 2 out of every 100 brain tumours (2%) are this type.