Uni had one on the top of her head, which we had removed during her spay. We had it biopsied and it was nothing. Then later I found another one on her elbow!
I have heard they could be follicular cysts, and usually are nothing. Keep an eye on them, if they get bigger or discolored then def need to be taken out and biopsied. I also found a blackhead (?) on Uni's inner thigh. I'm also monitoring that, but so far, nothing interesting. I just want all the weird bumps gone off my yorkie, and I am sure you feel the same!