Sir Elton 'grateful to be alive'
The star told The Sun he feels "grateful to be alive" after discovering the source of his recent "agony".
A series of shows including a headline performance at London's Hyde Park have been cancelled as he prepares to undergo surgery in the next few weeks.
He is receiving intensive treatment to contain the condition after a series of scans and blood tests by UK doctors to identify the source of his ill health.
Sir Elton, 66, told the newspaper: "I was a ticking time bomb. I guess I could have died at any time. I feel so lucky and grateful to be alive."
The veteran musician said he performed 10 concerts in pain, which he had thought was due to food poisoning, but was finally forced to walk off stage during a concert in Halle, Germany, on Friday.
Doctors advised him to cancel all the dates on his current tour.
A statement on behalf of the singer said he had been diagnosed with an "appendix abscess surrounding retrocaecal appendicitis".
He is expected to undergo surgery in the UK in the next few weeks when doctors are sure they have reduced toxins around the inflamed appendix sufficiently.
The singer's spokesman said Sir Elton will not return to touring until fully recovered from the surgery and the damage caused by the abscess.