Discoid lupus erythematosus is the most common type of chronic cutaneous lupus (CCLE), an autoimmune skin condition on the lupus erythematosus spectrum of illnesses. It presents with red, painful, inflamed and coin-shaped patches of skin with a scaly and crusty appearance, most often on the scalp, cheeks, and ears. Hair loss may occur if the lesions are on the scalp. The lesions can then develop severe scarring, and the centre areas may appear lighter in color with a rim darker than the normal skin. These lesions can last for years without treatment.Patients with systemic lupus erythematous develop discoid lupus lesions with some frequency. However, patients who present initially with discoid lupus infrequently develop systemic lupus. Discoid lupus can be divided into localized, generalized, and childhood discoid lupus.The lesions are diagnosed by biopsy. Patients are first treated with sunscreen and topical steroids. If this does not work, an oral medication—most likely hydroxychloroquine or a related medication—can be tried. Signs and symptoms
Morphology of lesions
Discoid lupus erythematosus (DLE) skin lesions first present as dull or purplish red, disc-shaped flat or raised and firm areas of skin. These lesions then develop increasing amounts of white, adherent scale. Finally, the lesions develop extensive scarring and/or atrophy, as well as pigment changes. They may also have overlying dried fluid, known as crust. On darker skin, the lesions often lose skin pigmentation in the center and develop increased, dark skin pigmentation around the rim. On lighter skin, the lesions often develop a gray color or have very little color change.
In addition, these patients have an increased, though still small, risk for aggressive skin squamous cell carcinoma. Causes
Sun exposure triggers lesions in people with discoid lupus erythematous (DLE). Evidence does not clearly demonstrate a genetic component to DLE; however, genetics may predispose certain people to disease. Mechanism
Most experts consider DLE an autoimmune disease since pathologists see antibodies when they biopsy the lesions and look at the tissue under the microscope. However, scientists do not understand the connection between these antibodies and the lesions seen in discoid lupus.Possibly, UV light damages skin cells, which then release material from their nuclei. This material diffuses to the dermoepidermal junction, where it binds to circulating antibodies, thereby leading to a series of inflammatory reactions by the immune system.Alternatively, dysfunctional T cells may lead to the disease. Diagnosis
When a patient initially presents with discoid lupus, the doctor should ensure that the patient does not have systemic lupus erythematosus. The doctor will order tests to check for anti-nuclear antibodies in the patients serum, low white blood cell levels, and protein and/or blood in the urine.In order to help with diagnosis, the doctor may peel off the top layer of scale from a patients lesions in order to look at its underside. If the patients do indeed have discoid lupus, the doctor may see tiny spines of keratin that look like carpet tacks and are called langue au chat.Diagnosis is confirmed through biopsy. Typical biopsy findings include deposits of IgG and IgM antibodies at the dermoepidermal junction on direct immunofluorescence.