There are two types of lupus:
Discoid lupus erythematosus (DLE)- DLE mainly affects the skin that is exposed to sunlight and doesn’t typically affect vital internal organs. Discoid (circular) skin lesions often leave scars after healing of the lesions.
Systemic lupus erythematosus (SLE)- SLE is more serious: It affects the skin and other vital organs, and can cause a raised, scaly, butterfly-shaped rash across the bridge of the nose and cheeks that can leave scars if untreated. SLE can also affect other parts of the skin elsewhere on the body. SLE can cause kidney disease. Brain involvement is rare, but for some, lupus can cause confusion, depression, seizures and strokes.
The disease may also inflame and/or damage the connective tissue in the joints, muscles, and skin, along with the membranes surrounding or within the lungs, heart, kidneys and brain. Blood vessels may come under attack with systemic lupus. This can cause sores to develop on the skin, especially the fingers.
Some lupus patients get Raynaud's syndrome, which makes the small blood vessels in the skin contract, preventing blood from getting to the hands and feet -- especially in response to cold. Most attacks last only a few minutes, can be painful, and often turn the hands and feet white or a bluish color.
Sources:
http://www.webmd.com/lupus/guide/understanding-lupus-basics