Paul Allen in a recent photo shoot at the Seattle headquarters of his Vulcan Inc. investment company. (Dan Schlatter/Puget Sound Business Journal)

Post updated with Allen's video message to guests.

An undisclosed medical procedure prevented Microsoft co-founder Paul Allen from personally accepting the Seattle King County Realtors' First Citizen award this evening at a celebration honoring the billionaire philanthropist at the Sheraton in downtown Seattle.

David Postman, a spokesman for Allen's investment firm Vulcan, declined to comment about Allen's medical condition.

In a short video message shown on massive screens in the hotel ballroom, Allen said he was honored to be recognized. He is the 70th recipient of the award, which honors public service in the community.

Allen was diagnosed and treated for Hodgkin's disease in 1983, three years before Microsoft went public.

Many of Allen's friends and former colleagues -- including Microsoft co-founder Bill Gates and U.S. Sen. Patty Murray -- celebrated Allen's contributions to the city, from the founding of Microsoft to the construction of the Experience Music Project to the purchase of the Seattle Seahawks. Murray asked guests to stand up if they had worked at Microsoft, had been involved in real estate deals in South Lake Union, had viewed a movie at Cinerama or had attended a Seahawks game -- all projects tied to Allen. At the end of Murray's comments, nearly everyone in attendance was standing.

"Seattle wouldn't be the same without Paul Allen," Murray said.

Tod Leiweke, who leads Allen's sports and entertainment ventures, referenced Allen's medical condition along with the many injuries at the Seattle Seahawks.

"With all of our injuries -- our boss is now out," said Leiweke.

But Gates -- who co-founded Microsoft with Allen in 1975 -- captivated the crowd with stories of the early days when he and Allen played around with new computers at the Lakeside School in Seattle.

Gates recalled some of the first visits to Allen's house, where he noted the number of books in every room. Gates said he considered himself a "pretty serious reader" until he encountered Allen and his immense in-house library.

Gates called Allen one of the most curious people he has ever met.

Gates also recalled sneaking out to work on a computer at a company in the University District, noting that Allen's parents were always a little more liberal about letting him sneak out.

Later, after Gates dropped out of Harvard to pursue his entrepreneurial dreams with Allen, the two became closer. Gates noted how he was introduced to guitarist Jimi Hendrix through Allen, joking that Allen never really explained the Hendrix song:  "Are you experienced."

Gates said he still chats regularly with his old friend and business partner, talking about philanthropy or sports. "He's not only brilliant, but a very loyal person," said Gates.