@seag47 – My husband gets those cysts on his back, and I do the same thing as you to remove them. He seems to think that this is the most sensitive area to have cysts drained, but I think he only assumes this because he hasn't had any on other parts of his body.
Many of his epidermal cysts on his back have a small hair growing out of them, so this tells me that a hair follicle has become inflamed. The easiest way for me to drain them is to stick my long fingernail underneath them and scoop upward. He yells out in pain, but it works much more quickly than pressing from both sides.