The Nevada State Athletic Commission made the revelation on Tuesday.
According to the report, Silva submitted an altered and/or substituted specimen to the commission prior to his January 1st unanimous decision win over Brandon Vera. A second sample, tested following the match-up, confirmed their original findings.
In the meantime, Silva is temporarily suspending pending an April 7th hearing, where he will be given the opportunity to speak on his own behalf before his penalty is decided. The American Top Team member will likely face a fine and suspension, as well as having the January 1st victory overturned to a no-contest.