Tiling over WATER STAINED Linoleum?

[KenB]

I'm wanting to tile my bathroom, it has existing linoleum over concrete floor. At one point before I owned the home, there was a leak around the base of the toilet, which caused the linoleum to be stained. Could it be mold growing inside the linoleum, or is it just a water stain? I can email a picture if someone can help. I have read online that it is OK to tile over linoleum, but I want to know if the water-stained area might cause a problem long term if I do that? Thanks in advance for your help...

[LazyPup]

my concern would be the condition of the subfloor under the linoleum. Tile is very critical about have a sound subfloor and waterspots on the surface usually indicate dri rot will be present in the wood.