Bottom of Macbook Pro monitor is not displaying correctly.
MacBook Pro (Retina, 15-inch, Mid 2015), iOS 9.2.1
Unfortunately, that looks like damage to the display panel. Most likely from the lid being closed on something that was still inside the MacBook. It is likely to need the screen replacing.
That is not the case. It happened when I plugged a thunderbolt cable in from a slave monitor.
Try a NVRAM reset:
https://support.apple.com/en-us/HT201295
If no success, make an appointment at an Apple store genius bar for a FREE evaluation.
Ciao.
Bottom of Macbook Pro monitor is not displaying correctly.