The discovery of a brain cyst has ended New Zealand Warriors legend Manu Vatuvei's hopes of continuing his professional boxing career and may mean he's never able to play rugby league again.

The Warriors' all-time leading try-scorer hasn't played since 2017, following 14 seasons in the Telstra Premiership and one in the Super League.

In 2018 he announced plans to launch a professional boxing career, but just before his first pro fight in December – which ended in the former Kiwi international securing a knockout victory – Vatuvei was told he couldn't fight again.

"I've got a cyst in my brain, so that's been tough," Vatuvei said.

"[There were] no symptoms, no nothing ... everyone had to do a [brain] scan before the fight and they found it then and tried to rule me out of the fight, but I went on with it and came out good.

"I had some fights lined up which were cancelled because of that."

After a ruptured Achilles led to him leaving Salford in mid-2018 with five months left on his contract, Vatuvei revealed he couldn't even bring himself to watch rugby league.

At this stage the 33-year-old is refusing to officially retire and said taking part in the latest series of New Zealand's Dancing with the Stars – which he won – had been a way of filling the void left by footy.

"I haven't really announced my retirement or anything because I'm still in denial that I can still play," Vatuvei said.

I've got a cyst in my brain, so that's been tough Warriors legend Manu Vatuvei

"It's always been tough, I never watched a game when I came back from England, I never watched a game and I never went to a game or anything.

"I was missing it and getting itchy feet all the time.

"That's something I'm still trying to heal from. It was one of [the] hardest moments, but when I did this dancing it made it easier for me to get over it.

"I had to get over it somehow ... it was a tough challenge for myself and I've enjoyed it."

This week Vatuvei joined Mate Ma'a Tonga in camp ahead of their clash with the New Zealand Kiwis at Mount Smart Stadium and said it had spurred his desire to return to rugby league at some level.

Vatuvei said medical advice is that the cyst was present through his career, leaving him hopeful of being cleared to continue playing rugby league.

"[Tonga camp] was a good opportunity for myself to come in and get amongst the boys again and get that feeling again. It's hard, but I'm just enjoying it at the moment," Vatuvei said.

"There's always a goal that I want to come back to the game. It all depends, I've still got some medical things that I've got to look at.

"Right now my mind and my heart is telling me I can still play but my body is saying no, so it's a constant battle at the moment.

"Right now I can't do any boxing, but with footy they said because I must've had it a long time ago, I must have been all good playing [with it].

"So I'm still deciding from there. Hopefully, I hear back from that soon and decide what my future holds."