Davina McCall has shared that she is undergoing surgery to remove a 14mm brain tumour, which was discovered during a routine health check.The 57-year-old former Big Brother host revealed on Instagram that she is among the rare three in a million people diagnosed with a "very rare" colloid cyst.Colloid cysts are benign, non-cancerous fluid-filled sacs found in or around the lateral and third ventricles of the brain, according to the London Neurosurgery Partnership.The Long Lost Family host explained that after consulting with multiple neurosurgeons and receiving "lots of opinions," she decided to have the tumour removed as it is "big for the space" in her brain, and could cause serious issues if it continues to grow. The Masked Singer judge mentioned she would be in the hospital for about nine days following the surgery and asked her fans to “pray for me,” though she reassured them that she was in "good spirits."