What's the deal with this unknown disfigurement on this possum?

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.