Anything producing light behind the MacBook? All apple laptops will show the apple logo through the screen if you shine a bright light behind it because it is built to allow the backlight from the LCD to also light up the apple logo. Yours could be some type of reflective film that was applied incorrectly and is showing up as a dark area instead of a lighter one like how it normally would.
If you attach it to an external monitor, what do you see? That is the first thing that I would check. Because that could reveal if this is just a screen issue or something further.
What version of OSX do you have installed? Because that really doesn't look like the Apple that I'm used to seeing when I boot my machine (when it had 10.8 or now Mavericks).
The guy who posted above me is right about pointing a light on the screen. When i got my Dell laptop about 6 years ago, I dropped it and was able to get my files off of it because I pointed a bright flashlight and was able to put all my files onto an external HD.
It likely IS something to do witht he Apple logo on the back of the display, but it's still not normal. My MacBook Air, MacBook Pro, and the laptops I had before these didn't do that.