Ricksen revealed this week he was diagnosed with the condition a month ago. The 37-year-old is undergoing further tests to discover how far the illness has developed. The disease is progressive and can kill in a matter of five years.
McCoist was not at Rangers during Ricksen's colourful, controversial and successful spell between 2000 and 2006. The Dutchman won two titles, two Scottish Cups, three League Cups and was voted joint SFPA Player of the Year with John Hartson in 2005. But McCoist and Ricksen got to know each other and the current manager paid him a high tribute by saying he would have fitted in with the leading characters of the nine-in-a-row era.
"It's shocking because you think young, fit sportsmen have an aura of invincibility about them," McCoist said. "You do think these things don't happen to young, fit people like that. But sadly they do. He was a great character when he was here. He would have walked right into our squad - he was that mad. And I mean that in the nicest possible way, as a compliment. He's have been a perfect addition with Paul Gascoigne, Ian Durrant, boys like that. He was a terrific footballer for Rangers as well.
"We hope he can fight it as much as he can. It's just terrible news and puts everything else in perspective. It goes without saying that all the thoughts of the staff here at Murray Park and Ibrox and all the support are just thinking about Fernando and his family at the moment.
"The punters loved him and rightly so. He had a mischievous streak which endeared him. He was special in that not everyone gets that bond with the fans. Fernando certainly had that. A lot of it was down to his ability as a player but also he had that wee spark. For a foreigner, he was very much like a home-based player in that respect. He totally grasped what it was about to play for the club and what was expected when you pulled on the jersey. He grasped that as well as any foreigner that I've seen."
In July it had emerged Rangers and Fortuna Sittard, the last club of Ricksen's career, were discussing a possible partnership on certain youth development issues and as part of an agreement there was to be a match between the clubs so fans could show their appreciation for Ricksen. That fixture could now go ahead, albeit in desperately sad circumstances.
"He was trying to organise a game between Fortuna Sittard and Rangers so there would be a relationship between the two clubs," said McCoist. "I think that's still on-going at the moment actually. Some kind of game for his benefit now would be great. We'd be open to anything we could do to help in any way we can. We always like to think of ourselves as a big family. When you leave the club, the ties stay for as long as life goes on. We would obviously be keen to do anything we can to help Fernando."