Depending on where they are located in the dermis, xanthelasma can be flat or rounded in appearance. It is possible that xanthelasma will form horizontally rather than in a lump if the weakest area in the skin layers is the layer in which the xanthelasma is situated.
It is termed xanthoma planar if they continue to expand in this manner. If left to its own devices, xanthoma planar can spread to cover the whole upper eyelids as well as the upper cheeks.