I'm not expert, but the head structure seems more mouse to me.
It's probably recovering from a mange, or some other condition. The lack of scabbing seems to indicate it does not currently have mange, but it could be a different condition (even stress) that has caused it to loose fur. Or even a mutation that caused the hair to not grow, but given the dimples where roots would be, that might not be the case.
I saw one just like this the other day, they said it was a hairless mouse in the process of losing its fur. The owner actually posted multiple pictures of the process. At first it looked like a werewolf and then it looked like it was wearing a tutu. lol.