apps I never purchased showing up in purchases?

I was going through my purchased apps, and I realized that there are two apps listed there that I never purchased or downloaded. It's a little alarming, especially since they are somewhat obscene. I'm very concerned about my account security and am wondering what steps I should take to 1) get them removed from my purchases, and 2) make my account secure again. I would also like to find a way to report the app developers for some unethical behavior. Any help or advice would be appreciated.