The England hooker missed Monday’s 22-0 home loss against Wigan Warriors - the club’s first defeat in five games - due to an abdominal injury.
It was feared it could be a serious issue but Tigers have received positive news and McShane hopes to feature against Salford Red Devils when Castleford resume their play-offs push in Newcastle on Saturday.
Powell said: “He had a scan yesterday. It’s not too bad.
“He’s had a bit of a run today and we’ll check him again in a couple of days time.
“We’re not ruling him out. Potentially he would play but we’re not 100 per cent certain at this point.”
Loose forward Adam Milner filled in at No9 against Wigan having impressed there when McShane went off injured early in the previous win at Hull FC.
Powell admitted having the 31-year-old back would be a big boost.
“Obviously Macca’s an important player for us," he said.
“He’s one of the best players in the competition so he’d be big for us.
“We missed him on Monday. Adam Milner did a great job the game before but with the short turnaround that was pretty tough on Adz when he doesn’t play there consistently.
“He (McShane) is a pretty important player for us.”
Powell said there is no tear in McShane’s abdomen and added: "It’s just bruising.
"But it’s in a real sore area so he’s got to get his head around that to start with and make sure he’s comfortable with it.
“Knowing Macca he’s a pretty tough human being so he’ll be wanting to play for sure.”
Winger Greg Eden is out, though, after suffering another hamstring issue against Wigan.
“Greg’s got a hamstring tear so he will be out but we have a couple of options on the wing,” added Powell, who is unsure if the 30-year-old will play again this term.
“He’s got to have a scan so we’re not certain of the severity of that.
“ Potentially if it’s a bad one it would be (season-ending).
“But I don’t think it is. We’ll have to wait and see.
“Adz tweaked his back against Wigan but he’ll be alright.”
Salford will be without former Leeds Rhinos prop Jack Ormondroyd due to concussion.