The 35-year-old's family released a statement on Tuesday announcing he had been admitted to Royal Melbourne Hospital after a routine blood test returned abnormal results but that a full diagnosis was yet to be made.
On Wednesday, Briony Lyle held a press conference in Melbourne and said her husband's cancer treatment had already begun.
“We've just received confirmation just a little bit earlier today that Jarrod does have a relapse of AML, which is acute myeloid leukaemia," she said.
"Now, probably as we're in this room, he's actually beginning his chemotherapy treatment, they'll be hooking him up and that will get started and that's going to be quite an intensive course of treatment."
Lyle posted the following message on his Facebook page early Wednesday evening.
"He's probably still in shock I'd say, and we probably all are, it's a bit surreal, and that's probably the reaction that we're also getting from a lot of people."
Lyle - who competed in 121 PGA Tour events between 2006 and 2016 - has twice overcome leukaemia, once in 1998 and again in 2012.
Several of the Shepparton native's Australian rivals on tour have extended their best wishes to Lyle and his family.
"So sad to hear about Jarrod Lyle back in hospital! He's inspired many and will do again I believe. He's an inspiration and a true hero!" former PGA Tour player Mark Hensby said via Twitter.
PGA Tour veteran Rod Pampling tweeted: "So sad to hear, fight hard Champ. We are all thinking of you and your family."
Web.Com Tour player Rhein Gibson tweeted: "I have no idea what is takes but [Jarrod] you have kicked its ass twice, let's make it three times. Thinking of you mate."
In September last year, Lyle, after missing out on securing his PGA Tour card, announced he would no longer compete in the US and was returning to Australia to be with family and compete locally.
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