Cincinnati Bengals coach Marvin Lewis missed practice Tuesday to deal with a cyst in his knee, a team source told NFL Network's Stacey Dales.
The team released a statement noting the issue is "minor" and that Lewis' absence is expected to be brief. The Bengals did not state the specific nature of Lewis' injury in the statement.
Lewis is taking medicine to break up what has been diagnosed as a Baker's Cyst. He was taken to the hospital Tuesday by team medical staff after his ankle swelled to twice its normal size due to blood thinners he was taking, Dales reported.
"Coach Marvin Lewis will be taking time away from the team to focus on a minor health issue," the statement read. "He will be back as soon as possible, which could be today or later this week. Special teams coordinator Darrin Simmons will lead the team during Coach Lewis' absence."
A Baker's Cyst is a fluid-filled cyst in the knee that can cause joint swelling, according to the Mayo Clinic.
Lewis, 58, enters his 15th season as head coach of the Bengals, compiling a 118-103-3 record with seven playoff appearances.
UPDATE: Lewis returned on Wednesday and will coach in the team's preseason game on Friday.