Pitkanen did not return after he left with 1:57 left in the second period. Coach Kirk Muller did not know the extent of the injury, which he said was either an ankle or heel.
Pitkanen was hurt when he raced down the ice while trying to beat an icing call and went hard into the boards with the Capitals' Troy Brouwer near him.
He was on the ice in obvious pain and was taken off on a stretcher with his hands covering his face.
Pitkanen -- who missed 14 games during the past two months with a lower-body injury -- has one goal and eight assists in 22 games.