Anderson is an 11-year-old who has been battling HLH - a life-threatening autoimmune disease - and was invited to Game 7 of the Stanley Cup Final in Boston, where she watched her St. Louis Blues earn a 4-1 win at TD Garden and was escorted to the ice for the postgame celebration. Colton Parayko - one of the players who befriended her after meeting her previously - took Anderson to get a photo with the Stanley Cup.

"Dear Laila - We have never met, so let me begin by introducing myself. My name is Marty and I am a passionate, lifelong Boston Bruins fan," Walsh's letter begins. "I am writing to you because a couple of weeks ago, I was at home, watching pre-game coverage of game 3 of the Stanley Cup finals, when I saw a story about you, your love of the St. Louis Blues, how the Blues players' love you in return, and how you inspried an entire city and fan base. After watching the segment, I turned to my partner, Lorrie, and said, 'This stinks! I love the Bruins and I want them to win! ... But I really want Laila to win, too!'"

Later on, Walsh writes: "I don't know if you or your family plan to come back to Boston anytime soon, but if you should return please let me know as I would be very glad to meet you and your family and show you some more of Boston. I certainly can't promise you a cooler experience than standing on the Garden ice kissing the Stanley Cup, but Boston's a great city and would love to have you back."

The complete letter was posted on Twitter by FOX Sports Midwest's Andy Strickland.

Tweet from @andystrickland: Boston Mayor, Martin Walsh sends inspiring #stlblues fan Laila Anderson a personalized letter congratulating her on the Blues #StanleyCup win pic.twitter.com/988Sx5HRFW