The suit names Pittsburgh Public Schools, Frick Middle School and its principal as defendants for failing to stop three boys from harassing the girl and calling her names on a daily basis, the Pittsburgh Post-Gazette reports.
The girl, identified only as B.G. was forced to withdraw from school and seek mental health treatment, the suit says.
"The offensive comments explicitly and implicitly conveyed the message that B.G. was unattractive and overweight," attorney Edward A. Olds said. "The comments were sexual in nature or conveyed sexual stereotyping."
School solicitor Ira Weiss said he can't comment on the lawsuit but the district plans to vigorously defend itself.