Indianapolis Colts head coach Chuck Pagano has been diagnosed with a treatable form of leukemia.

Pagano will remain hospitalized while undergoing treatment and will take a leave of absence. Offensive coordinator Bruce Arians will take over as interim head coach.

Colts owner Jim Irsay held a news conference Monday to disclose Pagano's condition and the coach's physician, Dr. Larry Cripe, described the outlook for recovery.

"It's been a difficult week," said Irsay on Monday. "Obviously, a very difficult blow for him and for his family.

"Chuck feels he can beat this thing. When you get a difficult diagnosis, it's tough. The case here is we feel that he will battle and get this disease in remission."

Pagano has been hospitalized and undergoing treatment since last Wednesday. He underwent blood tests during the Colts' bye week after feeling fatigued in recent weeks and developing bruising.

Cripe said the bruising was consistent with a form of leukemia, a cancer of the bone marrow tissue. The diagnosis of acute promyelocytic leukemia is considered to have a good chance of remission, although Cripe would not disclose percentages in Pagano's case.

"The goal of the treatment is to cure the disease," Cripe said Monday. "That means he returns to a fully functional life. The process is long and complicated and we're just starting right now."

Cripe added that Pagano will undergo about 4-to-6 weeks of treatment and will be released from the hospital once his blood count returns to normal levels. He will continue to undergo treatment once leaving the hospital, a process that could extend two years.

Irsay said he believed Pagano might be able to return to the team in a limited role later this season, saying he wouldn't be "all in," and indicating he might be able to help out from the press box.

Pagano, who will turn 52 years old on Tuesday, is in his first year as Colts head coach and has the team off to a 1-2 start.

Irsay said Pagano thought the bruising may have come from contact in practice or playing with his grandchildren, but said as it got worse, the coach's wife urged him to go for tests.

The Colts will take on the Green Bay Packers next Sunday and Irsay said the team would love nothing more than to take the game ball back to Pagano after a victory.