Kate Middleton shocked the world with a noticeable head scar.
Speculation about the scar led to rumors of brain surgery.
Reports revealed she had surgery during her school days.
A lump on her head was discovered at Marlborough school.
School informed Kate's mother, who rushed her to the hospital.
Emergency surgery removed the lump and left a scar.
Initial belief: scar from misplaced hair extensions.
Kensington Palace confirmed surgery in 2011 but didn't disclose the ailment.
Mystery still surrounds the exact reason for Kate's surgery.