United have confirmed that Robson was forced to undergo surgery in Bangkok earlier this month.
Although the problem is not serious enough to prevent him continuing in his twin role as Thailand national team boss and United's Far East ambassador, the 54-year-old will require further treatment.
Old pals: Bryan Robson (right) played under Sir Alex Ferguson (left) at Old Trafford and is now Far East ambassador for Manchester United
Ferguson spoke to Robson on Wednesday and was heartened by the typically bullish approach the man dubbed 'Captain Marvel' by Sir Bobby Robson was taking against the situation.
'We got the news about Bryan yesterday and I have been in touch with him,' said Ferguson. 'He is positive. That is the important thing.
'We are all supportive of him because he is such a fantastic man. He has always been a fighter and he will be all right. I am sure of that.'
Happier days: Robson and Ferguson celebrate winning the FA Cup in 1990
Robson has always been one of football's most popular figures despite his failure to replicate brilliance as a player into the management game.
Former England international and a successor as Middlesbrough manager, Gareth Southgate, is just one of those who have expressed their support for a man who won 90 caps for his country and captained Manchester United to three FA Cup successes and the Premier League.
'Best wishes to Bryan Robson - a fighter for sure (my boyhood hero!),' said Southgate on Twitter.
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Explore more:People: Alex Ferguson, Gareth Southgate, Bobby Robson, Bryan Robson Places: Bangkok, United Kingdom, Thailand