Sarah Ferguson, 64, had an op to look at a malignant mole and her lymph nodes following her diagnosis last month.
And pals have said the results were the “best possible outcome she could have hoped for”.
One said: “It looks like there has been no spread of the disease and the prognosis is good, but she’ll have to have regular check-ups going forward.”
A source added: “It’s a huge relief for Sarah and the entire family.”
It was Fergie’s second scare in a year, after she was found to have breast cancer last summer.
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She had a mastectomy and reconstructive surgery.
At the time of diagnosis, a spokesman for Sarah, Duchess of York said: “Following her diagnosis with an early form of breast cancer this summer, Sarah, Duchess of York has now been diagnosed with malignant melanoma.
“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 now wants to encourage more people to have regular mammograms to check for breast cancer, and to get their moles checked out.