The 30-year-old left-hander has been in US since last month being treated for what was earlier claimed to be a tumour in the lungs by his family.
But it has now been diagnosed as malignant and Yuvraj is currently undergoing chemotherapy in the Cancer Research Institute in Boston.
His physiotherapist Dr Jatin Chaudhary, however, assured that the ailment is curable and the batsman would be fit to resume cricket in May. His mother Shabnam Singh could not be reached while his former cricketer father Yograj refused comments on the matter.
"It is a rare tumour and is cancerous but it has been detected in stage one itself. Doctors had to decide whether to continue medication or go for chemotherapy but since parts of the tumour are just above the artery of his heart, there was a danger that while running it could burst. But it is 100 per cent curable," Chaudhary said.
"The doctors decided that he would have to undergo chemotherapy and he travelled to the US on January 26. End of March, he would undergo a CT scan and should recover by then. After that it is just some rehabilitation in April before he is fit to be back on the field in May," he added.
Yuvraj, who was Player of the Tournament in the World Cup last year with 362 runs, 15 wickets and four Man-of-the-Match awards, has also been taking ayurvedic medicines to battle the disease.
"After ayurvedic treatment only three cycles of chemotherapy are required. Initially when the cancer was diagnosed after a biopsy in October end, doctors feared that the treatment would be six cycles of chemotherapy," Chaudhary said.
"Thankfully no surgery is required, he is already a lot better than what he was and can't wait to be back on the cricket field," he said.
Chaudhary said the detection of cancer was delayed by wrong diagnosis by an Indian hospital.
"His first biopsy report was stolen from his car and the second from a hospital, I don't want to name, did not give the correct diagnosis. It was a Russian doctor who detected the cancer and after consultations with doctors in US, it was decided that Yuvraj would undergo chemotherapy," he said.
"Once he is done with chemo in March, his rehabilitation would be complete by April end and he would be perfectly fit to play in May," he added.
Yuvraj has played 37 Tests, scoring 1775 runs at an average of 34.80.
He has 8051 runs at an average of 37.62 from his 274-match ODI career, the highlight of which was his stellar role in India's World Cup triumph last year.
In 23 Twenty20s, Yuvraj has scored 567 runs at 31.50.