By Vicky Wong for BBC News
The Duchess of York smiles attending the Royal Family's traditional Christmas Day service at St Mary Magdalene Church on the Sandringham Estate in eastern England, in 2023. Photo: AFP
The Duchess of York has been diagnosed with malignant melanoma following the removal of a cancerous mole during treatment for breast cancer.
Sarah Ferguson had several moles removed and analysed while having reconstructive surgery following a mastectomy, her spokesman said.
The duchess "remains in good spirits", despite it being "distressing" to have another cancer diagnosis.
She is the third royal to announce a medical procedure in a week.
Her spokesperson said: "Her dermatologist asked that several moles were removed and analysed at the same time as the duchess was undergoing reconstructive surgery following her mastectomy, and one of these has been identified as cancerous.
"She is undergoing further investigations to ensure that this has been caught in the early stages.
"Clearly, another diagnosis so soon after treatment for breast cancer has been distressing but the duchess remains in good spirits.
"The duchess wants to thank the entire medical team which has supported her, particularly her dermatologist whose vigilance ensured the illness was detected when it was.
"She believes her experience underlines the importance of checking the size, shape, colour and texture and emergence of new moles that can be a sign of melanoma."
The statement also thanked the private medical team that supported the royal during her treatment.
The duchess confirmed a diagnosis for breast cancer last June, following a routine mammogram screening.
She went on to have a single mastectomy at King Edward VII hospital in London, a private clinic used by senior royals.
The 64-year-old was married to the Duke of York, Prince Andrew, for 10 years before they divorced in 1996.
They continue to share a home at Royal Lodge - a property owned by the Crown Estate at Windsor Great Park.
They have two daughters - Princess Beatrice, 35, and Princess Eugenie, 33 - and three grandchildren.
The duchess was last seen in public on Christmas Day attending a Christmas Day church service in Sandringham with the King and Queen and other senior members of the Royal Family.
She has not accompanied the family on the walk to the Christmas morning church service for more than 30 years.
It was confirmed on Wednesday that the Princess of Wales would remain in hospital for up to two weeks after planned surgery, and that the King would soon be treated for an enlarged prostate.
On Wednesday, Kensington Palace confirmed that Catherine would stay in hospital for up to two weeks after undergoing abdominal surgery.
Kensington Palace said the procedure was successful but that the princess was not expected to resume royal duties for months.
The palace did not disclose further details about her condition but said it was not cancer-related.
Shortly after that announcement, Buckingham Palace said the King would receive treatment for a benign prostate condition and will visit an undisclosed hospital in the coming days.
It is thought the King wanted to share his diagnosis with the public to encourage other men who may be experiencing symptoms to get checked.