Trent Williams says Washington Redskins doctors misdiagnosed his cancer more than FIVE YEARS ago ... and the 7-time Pro Bowl left tackle says it nearly cost him his life.
The 31-year-old -- who held out from the team earlier this season -- returned to the Redskins this week ... and in his first meeting with reporters, he made the stunning revelation.
Williams claims back in 2013, he approached team doctors about a growth on his head ... but says after they told him it was a benign cyst and nothing to worry about, he essentially ignored it.