LCS ready generally means its prepared for it, like on the full tower armor, it has 4 gasket covered holes in the rear for tubes to run in and out, and also has a mount for small rez tanks. some might mean there is an LCS available for that case made by the company.
If you want to liquid cool, its not a necessity to have a case that is LCS ready. like whitefiredragon said, you can put one in bust about any case, just some mods might be necessary.