anyone know what this is ???

found this last night on the right side of my boyfriend's ribs... he s calling for a dermatology appointment tomorrow but I'm wondering if anyone can tell me what this is ad I'm really worried.. he s never had a mole there or anything, could it be just a scab? it doesn't hurt or itch or anything, we didn't notice it last week I just happened to feel it last night. any help is appreciated .. once again he will be seeing the Dr asap I just wanted some idea of what it could be if anyone has had or seen this