Leaking Fluid From Left-Rear Brake

What is your question?

Almost a year ago, my left rear brake seized up. Grinding and Squeaking noises ensued. I kept putting off the needed repair(s)due to lack of funding and general stupidity. Now the car is leaking brake fluid from that wheel/brake. My mechanic hasn't taken an official look at it, but based on my description, he says it sounds like the wheel cylinder needs to be replaced. However, based on my research, I've gotten the impression that a wheel cylinder only exists in cars with drum brakes. I'm fairly certain my car has all disc brakes. I'm not faulting my mechanic as he has not actually looked at my car, and he's not a specialist on Acura Integras; So I don't expect him to just know, off-hand, that it's all disc. I wanted to know what actually is/are the potential necessary repair(s) so I can get a better idea as to the cost.