The coach said that Bell will only play if he can protect himself and that there is a chance the Steelers still sit Bell even if he's medically cleared.
The coach added that if Bell isn't able to go it's not an end-all: "There have been games where we did not have a significant contribution from him."
In Pittsburgh's Week 9, 43-23 victory over Baltimore, Bell had just 23 yards rushing on 10 carries and 38 yards on five receptions. Ben Roethlisberger threw for 340 yards in that contest.
Still, without Bell's services the Steelers would be stripped of the most dynamic dual-threat running backs in the NFL.
Replacing Bell's production would be a daunting task.
"Josh Harris is at the top of the list," Tomlin said of the backfield rotation. But added, "we're also not opposed to going outside the box."