Since her cancer diagnosis last year, the Princess of Wales has relied on her mother, Carole Middleton, more than ever.
Carole was prominent in Princess Kate's poignant three-minute family film announcing her preventive chemotherapy completion in September.
The typically healthy princess had avoided hospitals until lately, but she had one health scare that left her mother "very worried," according to Daily Mail.
Princess Kate found a tumor on her left head while boarding at Marlborough College, a £42,900 exclusive school.
After school personnel phoned her, Carole accompanied her daughter to their family doctor, who, according to royal biographer Katie Nicholl, termed the bulge "potentially serious."
After a few days of surgery, Princess Kate's skull had a three-inch scar.
Princess Kate's school housemistress, Ann Patching, told Nicholl: "I can remember the incident and her having an operation."
"I don't recall anything happening on the hockey pitch (field) that had anything to do with the lump," she stated after media suggested a sporting injury may have caused the health issue. Princess Kate led the hockey team at Wiltshire school.
In her 2013 book "Kate: The Future Queen," Nicholl calls the procedure her "only unhappy spell" at the school since it ended her sports career.
Patching said, "Princess Kate had the operation during her term time." She returned to school quickly.
"As usual, nothing was too much of a big deal for her. You could never accuse Princess Kate of being a drama queen, but Carole was very worried, as any mother would be," she added.
The procedure "was quite severe" and scared everyone, according to a former student, as Hugo McDermott had died from a brain tumor just before.
After the procedure, Princess Kate's scar faded and was generally disguised by her loose hair.
The princess's first solo royal engagement, a black-tie luncheon at Clarence House, revealed the flaw in 2011. An official statement noted "the scar related to a childhood operation" but did not disclose the surgery. Royal sources called it "a very serious operation"' but declined to elaborate.
Consultant surgeon John Scurr at the Lister Hospital in south-west London said the scar was unlikely to represent a cancer.
"I really doubt it was any serious medical condition and I would say it is as a result of an arteriovenous malformation a birthmark being removed," he said. "It is remarkable, given the measurement, that no one has noticed before."
Like many others, Princess Kate has a significant childhood scar on her head. At 13, a golf club hit her husband, Prince William, leaving a big zig-zag mark on his forehead. Nicholl says the couple call their wounds "Harry Potter scars" privately.
According to Hello!, he was injured in 1991 while playing golf with schoolmates in Wokingham. The eight-year-old prince had surgery at Great Ormond Street Children's Hospital for a broken skull. Playing sports inflames the scar.
Princess Kate's uncommon health concern has elicited a multitude of responses from internet users. This is an examination of public reactions.
"I had no idea about this. Glad Kate is okay! Strong woman," one netizen said.
"It must have been such a tough time for her. So glad she got through it," another person wrote.
"Carole must have been so worried. Every mom's nightmare!" a third user said.
"Her resilience is inspiring. I can't imagine going through something like that at her age," a fourth chimed in.
"So many secrets in the royal family. Wonder what else they're hiding," a netizen said.
"This really makes me admire her even more. She's so strong," another fan gushed.
Business Times has reached out to Princess Kate for comments.
