Tom Sizemore Sued for Alleged Child Sex Abuse of 11-Year-Old Girl

Tom Sizemore inappropriately touched an 11-year-old child actress who was working with him on a film in 2003, and it caused lifelong damage ... according to a new lawsuit.

Sizemore is being sued in Utah by Kiersten Pyke, who claims Sizemore groped her on set when she was 11 years old during production of the movie "Born Killers" -- in which they were both starring. The suit alleges Sizemore touched the girl underneath her underwear during a scene, and placed his finger in her private parts. This allegedly happened in the presence of about 20 people, including the girl's mother.

The lawsuit goes on to claim the woman suffered irreparable damage as a result of the alleged incident -- including mental, psychological, and emotional problems, substance addictions, PTSD, emotional instability ... and lots of other problems.

According to the complaint, Sizemore was initially removed from the project after the allegation surfaced at the time -- but the alleged victim claims he was ultimately brought back to finish the movie ... and that she was the one who ended up getting the ax.