Consider the following code:

class B
{
  internal C Owner { get {... } }
}

class C
{
   private int id;

   void M(B b) 
   {
      Console.WriteLine(b.Owner.id);
   }
}

If Renamer.RenameSymbol is run on the fieldC.id the rename operation will not update the reference in the expression b.Owner.id.