The 22 year-old singer snapped a photo in an L.A. ER, presumably of the wound -- but just like the rest of her Instagram ... she photoshopped a happy face.
We're told it was a hospital in Tarzana -- the San Fernando Valley -- and she was there Friday afternoon. We don't know what caused the injury.
Miley also posted a pic of herself wearing the gown and noted how hipster it made her look.
