The Duchess of York has spoken of her “shock” at being diagnosed with malignant melanoma, a form of skin cancer, but is in “good spirits”.

In an Instagram post, she said she was “grateful for the many messages of love and support”.

The melanoma was discovered following the removal of a cancerous mole during treatment for breast cancer.

The duchess, Sarah Ferguson, had several moles removed and analysed while having reconstructive surgery.

The duchess is the third royal to announce a medical procedure this week.

“I have been taking some time to myself as I have been diagnosed with malignant melanoma, a form of skin cancer,” she said on Instagram on Monday.

It was her second cancer diagnosis within a year after being diagnosed with breast cancer in the summer and having undergone a mastectomy and reconstructive surgery.

“Naturally another cancer diagnosis has been a shock, but I’m in good spirits and grateful for the many messages of love and support.”

On Sunday her spokesman had 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 was undergoing further investigations to ensure this had been caught in the early stages, he added.

“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.”

According to sources close to the duchess, she is back in the UK after initially recuperating in Austria.

A second cancer diagnosis within six months is clearly a great challenge to deal with, say sources, but she is a resilient person and is getting the care and support of her family.

The duchess has shown a remarkable ability to bounce back from adversity.

Last year, she had a diagnosis of breast cancer, following a routine mammogram screening.

The duchess was very public about her treatment, urging other women to get checked and using her podcast to raise awareness about breast cancer, wanting it to be a positive message to save others.

She went on to have a single mastectomy at King Edward VII hospital in London, a private clinic used by senior royals.