One of the main themes of the limited HBO series, Sharp Objects, is that the main character, Camille Preaker, portrayed by Amy Adams, deals with childhood trauma by carving words into her own flesh. Many of these words are symbolic to her experiences and are used to tell parts of her personal history.
It is revealed that she carved words clearly on her back. I think this would be physically impossible to do, but the character says that she doesn't let anyone see her carvings so it's not likely someone else helped her write these words.
Maybe a book reader would have more information on the topic?