Why a triangle shaved on a cat's back?

[Tonya]

I put the dogs out around 3am last night. Shortly after, I heard a bunch of commotion and I ran outside. Dusty had a beautiful Blue Point Himalyan (I think). She's declawed, so she couldn't escape. She's ok. (I am sooooo disappointed in Dusty, btw.) Anyways, she's got a perfect triangle on her back above her bottom. It is so perfect that it appears to be shaved. Is that a symbol of something? Like a recent surgury?

*edit* Here are some pics of her. They aren't that great, sorry. She's litterbox trained and so sweet. The vet suggested that it may be fur shaved for a mat or an abcess. -Probably a mat because the skin looks fine.