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Browns rookie Barkevious Mingo (with teammate Kendrick Adams) could do little more than listen to linebackers coach Brian Baker during Wednesday's practice at Berea.

(John Kuntz, The Plain Dealer)

BEREA, Ohio -- Barkevious Mingo's bruised lung could keep him out of football for months, considering he was spitting up blood and doesn't recall a sharp blow to the chest, two thoracic surgeons told cleveland.com Wednesday.

What's more, when the bruise heals, the Browns' rookie linebacker will likely have to undergo a battery of tests to rule out a more serious condition.

"The fact that he's spitting up blood means it's not a minor contusion,'' Dr. Philip A. Linden, Chief of Thoracic Surgery at University Hospitals Case Medical Center, said. Linden has not treated Mingo. "There's something significant going on there.''

Linden said a bruised lung can take anywhere from two weeks to two months to heal, depending on the severity of the contusion.

"Two weeks might not apply in this case because of the coughing up blood,'' he said. "The most common situation we see with lung contusions is after a motor vehicle accident, where there are broken ribs. Even then, coughing up blood is unusual.''

Linden said it's unusual because bruises usually occur at the edges of the lungs and "to cough up blood, it's usually something more central going on.''

Dr. Clark Fuller, Director of Thoracic Surgery at Saint John's Health Center in Santa Monica, Calif., said he wouldn't plan on Mingo being ready for the opener Sept. 8 against the Dolphins. He agreed that the issue could -- and probably should -- take months to resolve.

Last week, Fuller said he'd keep Mingo sidelined for at least two to three weeks -- but that was before Mingo revealed the blood.

"The opener is in jeopardy -- and it should be,'' said Fuller. "You've got to make sure this isn't a warning flag for something more serious. Spitting up blood and being short of breath shows you how severe it was, and there's no apparent reason for it.''

Both surgeons are puzzled as to how Mingo was injured lung without a sharp blow to the chest.

"A pulmonary contusion would be very unusual without significant force, such as the force that you would have with a bad motor vehicle accident on the chest wall,'' said Linden.

So what would explain Mingo's injury?

"I don't have an explanation for that,'' Linden said.

Mingo experienced shortness of breath after covering the opening kickoff of Thursday's 24-6 victory over the Lions, but re-iterated Wednesday that he did not take a helmet to the chest. As the first quarter wore on, he found it increasingly difficult to breathe, and had blood in his mouth. He alerted the training staff, who quickly took him to the Cleveland Clinic Hospital, where they diagnosed the injury.

On Tuesday, coach Rob Chudzinski said of Mingo's estimated date of return, "basically, the bottom line with KeKe is nobody really knows.''

On Wednesday in the locker room, Mingo insisted he felt fine in camp until that first play against the Lions, suggesting the cause of his injury didn't happen in the preseason opener against the Rams or in practice.

"It happened in the (Lions) game,'' he said.

Linden said another cause for spitting up blood is a clot in the lung that can mimic a contusion, "but I assume they've done the tests to rule that out.''

Browns right guard Jason Pinkston suffered a blood clot in his lung last season. He missed the final 10 games and remained out of football activities for six months while on blood thinners.

Fuller said he'd also want to rule out a congenital condition, such as an arteriovenous malformation, or nodule on the lung, which can rupture and be very serious.

"You need to know why this young man bled,'' he said. "Otherwise there's a huge risk out there and it could happen again."

He said the fact it occurred after a 30- or 40-yard sprint is significant. "It could be something he was born with, or maybe he tore something in his lung,'' he said. "But exertion triggered this thing, and right now an investment in a couple of weeks is small change compared to this young man's life.''

Fuller stressed that the lack of an obvious trauma to the chest is the biggest reason to exercise caution. He said that in the case of Chargers receiver Eddie Royal, who suffered a bruised lung in practice last Friday, he came down hard on his back and also suffered a concussion.

"That was one plus one equals two,'' Fuller said. "Here, we've got one plus one equals we're not sure. It's really difficult to put together, and quite honestly it's a little frightening because we don't have a good reason why he started bleeding inside his lung. I think it really needs to be fleshed out before this guys goes back out onto the field.''

Mingo said Wednesday that he's felt great since since spending Thursday night at the Clinic and that his breathing is fine. But his doctors -- who saw him again on Tuesday -- aren't letting him run yet. During practice, he's getting tips from fellow linemen, including left tackle Joe Thomas.

"I'm good,'' he said. "I can always take this time to get the mental reps and go out there at practice and watch the guys do it the right way and in the meeting room get the corrections and whatever it may be to get better."

But Fuller cautioned that he wouldn't rely on Mingo's reports of how he feels and his eagerness to play.

"Him feeling well has zero input into the management of his case,'' said Fuller. "The least important thing to me is how he feels. These things are a big deal, and it needs careful investigation to make sure nothing will raise its ugly head in the future.''