A 4-year-old leukemia patient from Ireland will march alongside New York’s finest in the largest St Patrick’s Day parade in the world.

For Ceejay McArdle, from Castleblayney in Co Monaghan, the invitation to walk with the New York Police Department in the parade on March 17 is a dream come true.

Said his dad Marcus: “A guard in Castleblayney, Derek Rochford, was in touch with the Emerald Society in New York and between them they set the invitation up.

“It’s an incredible gesture and they have even organized for Fitzpatrick’s hotel in New York to take care of the accommodation.”

Ceejay made headlines last year when he appeared at a Garda passing out parade in Templemore, the Irish Mirror reports. He was made an honorary Garda last September at Garda Headquarters.

nice touch by @GardaTraffic making Ceejay McArdle a garda for the day at the passing out ceremony in templemore pic.twitter.com/u2ZEgZqcGo

— Damien Eagers (@deagers) June 8, 2016

However, before Ceejay and make the trip across the pond with his dad and mom, Susan Brown, the family has to settle the matter of his cancer treatment.

Marcus said: “He hasn’t been well this week, he’s had a virus and has been in the Lourdes Hospital in Drogheda, and despite the big trip being on the horizon we can’t lose sight of the fact he is still battling a serious illness.

“The treatment he is undergoing has an 80% success rate so we have every reason to be optimistic about the eventual outcome.

“We have had to produce a letter from doctors in Crumlin Children’s Hospital to establish it is okay for him to fly and we had to source a hospital with an Oncology unit in New York in case we need one when we are there.

“Ceejay has started playschool and is in the final year of what doctors always told us was a four-year medical plan, he’s doing well despite this week's setbacks.

“And he’s delighted he’s going to meet NYPD members who have sent him so many kind messages."

Ceejay was diagnosed with leukemia in September 2014 and will be going through treatment until January 2018.

Read more: The tragic NYPD Irish cop who wrote one of Ireland’s best-known ballads

Ceejay McArdle, a 4-year-old leukemia patient from Ireland, will march in NYC’s St Patrick’s Day parade.Facebook/Ceejay McArdle