Tomlin didn't provide any additional information about Brown's potential return for the postseason.
ESPN's Adam Schefter previously reported Brown's injury as a partially torn calf muscle and noted the Steelers expect him back for the playoffs. Pittsburgh (11-3) has already clinched the AFC North and will secure a first-round bye if it finishes the regular season with a better record than the Jacksonville Jaguars (10-4).
Brown left the Steelers' 27-24 loss against the New England Patriots on Sunday in the second quarter. He was helped off the field and taken to the hospital for testing after suffering the injury.
The 29-year-old Brown leads the NFL with 101 receptions, 1,533 receiving yards and 109.5 receiving yards per game. He has caught at least 100 passes in each of the last five seasons.