Her family claims the hospital lost the tumor before performing a biopsy to determine if it was cancerous.
The Morris family says without the tumor, they will never know whether Kara has a potentially deadly disease.
"My daughter has gone through fear that no 18-year-old child should ever have to go through," said mom Charlene Morris. "Every day, she lives in fear. And the reason for our lawsuit is that we do not want any other family to go through this. We need it to change."
Children's Memorial Hospital said it's not commenting on the pending litigation.