Cutaneous lupus erythematosus, the skin-related form of lupus, affects people with systemic lupus erythematosus (SLE), but can also occur on its own. Cutaneous lupus erythematosus is an autoimmune disorder that affects millions of people worldwide. Approximately 85 percent of people with SLE will have a cutaneous manifestation of the disease at some point during their disease (1). About 20 percent of systemic lupus patients originally present with skin findings, which is the second most common initial symptom (2) and would be critical to early diagnosis.

Cutaneous lupus erythematosus has been classified into three major subtypes: acute cutaneous lupus, subacute cutaneous lupus erythematosus, and chronic cutaneous lupus erythematosus, with discoid lupus being the most common subtype (3). A butterfly-shaped (malar) rash on the cheeks and nose that is triggered by sunlight exposure is indicative of acute cutaneous lupus erythematosus. Subacute cutaneous lupus erythematosus is characterized by either ring-shaped red patches with scaly borders and lighter centers, or scaly red bumps in sun-exposed areas. Discoid lupus lesions are composed of red scaly plaques with both light and dark pigmentation, scarring, and skin thinning.

While the overall picture of the development of cutaneous lupus is still being elucidated, it is thought that a complex network of multiple factors that cause systemic lupus is behind the etiology of cutaneous lupus. These factors include environmental triggers including medications, viruses, and sunlight, and abnormalities in various genes related to the immune system (4). In particular, sun exposure is an important activator of cutaneous lupus. Ultraviolet light radiation can cause skin manifestations in cutaneous lupus patients by promoting cell death. These dead cells, in turn, become targets for autoantibodies. Antibodies are normally produced by the immune system to recognize foreign proteins in the body, which could be due to an infection. On the other hand, autoantibodies are abnormal antibodies since they react to the body’s own proteins and cause inflammation and damage to the body. In addition, ultraviolet light radiation also promotes the release of mediators called cytokines, which can ultimately activate and recruit inflammatory cells (4). An individual’s genetic makeup also likely predisposes him or her to cutaneous lupus. For instance, various genes important in recognition of foreign proteins (i.e. major histocompatibility complex genes) have been identified with higher frequency in cutaneous lupus patients (5). However, it is still unclear how these genes exactly lead to the formation of cutaneous lupus lesions. In summary, genetic, environmental, and immunological factors can contribute to the development of autoimmune reactions resulting in cutaneous lupus, and approaches to mitigating these causative factors are actively being sought.

Similar to systemic lupus, cutaneous lupus appears in approximately twice as many females as males (6). The highest peak of onset occurs in individuals in their 3rd and 4th decades of life (7). While African Americans appear to be more likely to develop discoid lupus than Caucasians, subacute cutaneous lupus patients show the opposite trend, with 85 percent of them being Caucasian (7). Although a specific genetic makeup can be a risk factor for cutaneous lupus development, the vast majority of cutaneous lupus patients do not appear to have relatives with systemic lupus (8).

There is no cure for cutaneous lupus; it is, rather, a chronic disease that can be controlled by a variety of medications and lifestyle changes such as limiting sun exposure through use of sunscreens and sun-protective clothing. The following are examples of treatments currently being used for cutaneous lupus:

• Sun avoidance: Sun protection is a very important proactive measure to prevent skin lupus flares caused by UVB radiation. Physical sunscreens (clothes, wide-brimmed hats) as well as chemical sunscreens (lotions) are effective at blocking harmful ultraviolet radiation that can precipitate lupus-related rashes and other skin manifestations.
• Steroids: These anti-inflammatory agents can be applied directly on the skin (topical), injected into the skin lesions (intralesional), or taken by mouth (oral). Prednisone is a commonly used oral corticosteroid that is reserved for severe disease and can quickly mitigate cutaneous lupus lesions. Its mechanism of action involves decreasing antibody production and inflammatory cells.
• Anti-malarials: This group of drugs, which include hydroxychloroquine, chloroquine, and quinacrine was made to initially treat malaria, but has also anti-inflammatory properties. The mechanism of action of these drugs is unknown. These drugs are often used as the first oral medications in cutaneous lupus because their side effect profile is less serious as some of the other oral medications.
• Mycophenolate mofetil, azathioprine, methotrexate: These immunosuppressive medications are reserved for severe disease, and are long-term options for cutaneous lupus patients attempting to wean themselves off of oral steroids. They are thought to affect DNA synthesis, which would decrease production of inflammatory cells.
• Thalidomide: Another long-term option for cutaneous lupus patients with severe disease, thalidomide is an inhibitor of a cytokine called TNF-α. Impeding the activity of this cytokine will decrease the severity of the immune response.