In Chinese Mahjong, when you already have a Kong in your concealed hand, do you reveal it?

In Chinese mahjong, I understand that if I pick up a tile that makes a Kong, I then pick up a replacement tile to keep my hand count correct, but I'm not clear how it works if I started with a Kong in my concealed hand.

Can I call Kong and reveal it if I didn't create it from picking up a discard? If I can't, I feel like I'm stuck with the Kong, or would I discard one of the tiles and treat it as a Pung and a single?