New to Psoriasis

[Lookingforhelp]

Does the skin only thin on the area the cream is put on or would it affect areas nearby?  The part where I see the veins is actually not the part that I put the cream on at all, but is next to it, however none gets on this area.  Would the cream cause the skin nearby to thin, or only the skin where the cream is directly applied?  If only the skin that the cream is directly applied onto, then I must just be worrying too much.