Sue Perkins has had brain tumour for eight years
Great British Bake Off star Sue Perkins has revealed she has a non-cancerous tumour in her pituitary gland, which prevents her from having children.
Speaking to Good Housekeeping magazine, the broadcaster said she had discovered the tumour while having medical tests for another BBC show, Supersizers.
"I'm lucky that it's benign so it's not in itself a worrying thing," she said.
"Sometimes it's big and makes me mad, and sometimes it's small and is in the background," the 45-year-old added.
"Sometimes it screws up my hormones. I have various tests now to make sure the side effects aren't too onerous."
The star subsequently thanked fans for their messages of concern.
She tweeted: "Ta for sweet tweets about my prolactinoma. It's benign & non-symptomatic. All fine."
"Let's focus on those less fortunate in the world," she added.
Perkins presents the hit BBC baking show with her comedy partner Mel Giedroyc; and is in a relationship with TV producer and journalist Anna Richardson.
She told Good Housekeeping that the growth affects the secretion of reproductive hormones, which means she cannot have children.
"I don't know if I would have gone on to have children," she said. "But as soon as someone says you can't have something, you want it more than anything."
Analysis: pituitary brain tumours
Smitha Mundasad, health reporter
Though just a small, pea sized gland on the underside of the brain, the pituitary is a crucial and complex hormone powerhouse.
It not only produces many different hormones, it also helps control and coordinate the release of others throughout the body.
The hormones help regulate many key processes - from metabolism, growth, sexual maturation and reproduction to blood pressure.
Tweets suggest Sue Perkin's has a prolactinoma - a tumour that secretes the hormone prolactin.
This is normally a benign, slow growing tumour.
They can have various side effects, for example, inducing milk production in the ducts of the breasts or sometimes infertility. Others can have no symptoms.
Prolactinomas can sometimes be treated using tablets to reduce the prolactin produced.
Other pituitary tumours can produce steroids, alter the levels of testosterone or oestrogen. or cause the thyroid gland to become overactive for example.
The new series of The Great British Bake Off was watched by 9.3 million viewers last month - more than two million up on last year's opening episode.