There's a baby possum that's kind enough to be a regular visitor where I am. Poor kid has what appears to be a wound on his/her face, almost like a cleft lip. I am no veterinarian, but a "code of honor" relevant to my hobby here casts a shadow over me and I was wondering what kind of issue the disfigurement represents so I don't feel guilty.
It's probably damage from some sort of attack. As bad as it looks, if it's not infected, bleeding, or hindering it's ability to eat, it will probably survive it. Opossums are tough buggers.