Catherine, Duchess of Cambridge, still popularly known as Kate Middleton, wrote a letter to a young cancer patient she met in September on a visit to The Royal Marsden Hospital's Sutton, Surrey location.
The letter to 9-year-old Fabian Bate was dated Oct. 13.
E! posted the letter, which had been scanned, on their Web site.
The letter was typed on St. James Palace letterhead with the letter C at the top. The duchess wrote Dear Fabian and signed it Catherine.
Despite the enormously demanding course of treatment you are undergoing, I was so touched by your strength of character, and delighted to hear the news that one of your big sisters will be able to donate bone marrow to you later this year, the duchess wrote.
She even mentioned young Fabian's blog, which he reportedly told her about when they met last month.
I'll look that up and post a message, the duchess said to him, the UK's Daily Mail reported.
Fabian's family commented on the letter to the Evening Standard.
It was a very personal letter, Fabian's father, Darrell, said. It certainly didn't look like the standard templates these official letters so often use. It contained very specific information that she must have remembered. We were very touched as she must do a lot of this stuff and to remember Fabian is very moving.