ESPN Eagles reporter Phil Sheridan outlines the process that could land offensive lineman Lane Johnson a 10-game suspension and describes what depth the team has available to replace him. (1:54)

PHILADELPHIA -- Eagles offensive lineman Lane Johnson, who signed a five-year, $52.25 million contract extension in February, is reportedly facing a 10-game suspension for violating the NFL performance-enhancing-drug policy.

Fox Sports reported that Johnson said he took an approved amino acid but tested positive for a banned peptide. He is appealing the suspension, which was first reported via Twitter by Wildfire Radio and confirmed by NFL Network.

"We are aware that a member of the media has started a rumor that Lane Johnson will be suspended for a PED violation," said Johnson's agent, Ken Sarnoff, in a statement released to ESPN on Tuesday. "Lane has not been suspended and any report to the contrary is false. None the less we will not comment on my client's protected health information."

The Eagles have not commented.

Lane Johnson served a four-game suspension in 2014 for using a medication that was on the NFL's list of banned substances. Another violation of the NFL's PED policy would result in a 10-game ban. Eric Hartline/USA Today Sports

Johnson, 26, was suspended for four games in 2014. At the time, Johnson said he had taken a prescription medication without checking with the Eagles' medical staff. The medication was on the NFL's list of banned substances.

The Eagles drafted Johnson, a 303-pound tackle from Oklahoma, with the No. 4 pick in the 2013 NFL draft. He has played in all 45 games, including a playoff appearance, that he was eligible for in his three seasons with the Eagles.

When the Eagles negotiated a contract extension during the offseason, it was with the intention that Johnson would eventually move to left tackle to replace 34-year-old Jason Peters. The contract included a $10 million signing bonus and a total of $35.5 million in guaranteed money.

If Johnson is suspended, including this year, he has $23.06 million in base salary guarantees that would void and no longer be guaranteed, league sources told ESPN's Adam Schefter.

Johnson would also be subject to forfeiture and have to pay back money he received for both his signing bonus and 2016 roster bonus ($2.437 million). By most accounts, sources told Schefter, Johnson would need to repay $1,176,471 of the signing bonus and $286,734 of the roster bonus from this year.

The Eagles have planned to replace Peters. They would have a tougher time replacing Johnson. Veterans Andrew Gardner, Matt Tobin and Dennis Kelly would be the most likely replacements. Tobin is scheduled to start at left tackle in Thursday night's preseason opener against Tampa Bay. Peters is out with a quadriceps injury.

Rookie Halapoulivaati Vaitai, a fifth-round draft choice this year, would be another possibility at right tackle. So would Allen Barbre, who has played tackle in the past, but that would entail making a change at left guard.

If Johnson is suspended for 10 games, he would be eligible to return for the Eagles' Nov. 28 home game against the Green Bay Packers.