We have a trapped 2 inch drain in the floor of the old laundry room that we are making into a bathroom. The floor is slightly sloped to the drain. It is a concrete basement floor. Question... To create the shower over the existing drain, do we need to get a poured cement pan or can we build a frame around it and tile directly on the existing cement floor? So, the floor of the shower would be the concrete floor of the basement with tile on top.

Why bother tiling the floor at all? Just enclose the sloped floor and you have a basement shower without all the hassle. My father did that in our old home back in Wisconsin. However, if you wish to tile and the slope's correct you could lay a thin layer of mortar down and tile directly to the existing cement. Good luck, Tom