McCall described it as a “big” tumour, 14 mm wide, adding: “It needs to come out, because if it grows, it would be bad.”
The Standard looks at what a colloid cyst is and how it is treated.
A colloid cyst is a benign cyst filled with fluid that develops near the centre of the brain.
It can cause headaches, vomiting, visual changes, memory difficulties and occasionally cause loss of consciousness or coma.
Colloid cysts account for less than two per cent of all primary brain tumours, according to information published in the National Library of Medicine.
According to the NHS, non-cancerous brain tumours are more common in people over the age of 50.
A colloid cyst can be fatal when it is allowed to grow but this is rare, scientists say.
The tumours tend to grow slowly and they do not spread to other organs in the body – unlike malign tumours.
Doctors tend to discover a colloid cyst during a routine check-up or CT scan, when it is asymptomatic.
How is a colloid cyst treated?
If patients experience symptoms, then prompt surgical treatment may be required to reduce the risk of sudden death, according to UCLA Health.
Other patients can have the tumour removed using an endoscopic removal, which is a minimally invasive procedure.
Some colloid cysts grow so slowly that they can be watched for years or even decades without issues, while others increase in size and require treatment.
McCall is having it removed through a craniotomy, a surgical procedure to temporarily remove part of the skull, and said she is in “good spirits”.
Her sister Caroline Baday died from lung cancer in 2012 at the age of 50.
She has previously raised money for Cancer Research UK by running for Race For Life in honour of her late sister.