Some Lupus sufferers have developed scleroderma (another auto-immune disorder) which causes their skin to become very dry and sometimes thick. I have heard some say that their scleroderma occurred where their lesions were and caused very dry skin in those areas. Collagen creams have been said to be helpful.
Perhaps someone else will have better information for you. I hope that you are able to find some relief.
Peace and Blessings