I just detected a little lump on Luna*s skin, near her shoulder blade. First I thought it was a tick (has the size and the shape of one) but it's not. It's doesn't seem to hurt her; in fact, she purred when I found it. It's very hard and solid and seems to grow out of her skin, so I hope it's no fibrosarcoma, but I'll take her to the vet tomorrow.
Tried to take a photo of it, but it didn't turn out well.
Needless to say, I'm a little worried now...