Pigmentary issues on face need not be only Sun induced , when u have such a pigmentation on the temples You will have to look in to lifestyle changes which maybe gradually over a period of time cause this kind of darkening One of the common cause of pigment on sides is metabolic melanosis which is caused when there is a sedantary lifestyle ,eating timings are varied, stress and lack of exercise , this leads to insulin resistance and darkening of face neck fold arm fold n thigh folds. Will have to get evaluated to check the reason why and take proper medication but life style is something which can do wonders on this if u start making the changes.