Cutaneous Lupus Erythematosus (CLE) is a chronic autoimmune disease characterized by inflammation primarily restricted to the skin. CLE is one manifestation of lupus erythematosus, where the immune system mistakenly targets healthy tissues. CLE can exist on its own or occur alongside systemic lupus erythematosus (SLE), a more widespread form of the disease. While CLE is less severe than SLE, the resulting skin lesions can cause discomfort, cosmetic disfigurement, and long-term scarring.
The Major Forms of Cutaneous Lupus
CLE is broadly classified into three main types. Acute Cutaneous Lupus (ACLE) is characterized by the classic malar rash, presenting as redness and swelling over the cheeks and bridge of the nose. These lesions are transient, tend to follow sun exposure, and heal without leaving scars. ACLE has the strongest association with active systemic disease.
Subacute Cutaneous Lupus (SCLE) lesions appear as either scaly, red patches resembling psoriasis (papulosquamous) or as circular, ring-shaped lesions with central clearing (annular). These rashes are highly photosensitive and appear most frequently on sun-exposed areas of the upper body, usually sparing the central face. SCLE lesions do not cause scarring but can result in temporary or persistent changes in skin pigmentation.
Chronic Cutaneous Lupus (CCLE) is most often seen as Discoid Lupus Erythematosus (DLE), which accounts for the majority of CLE cases. DLE presents as thick, scaly, disk-shaped plaques, often red or purple, commonly occurring on the scalp, ears, face, and other sun-exposed skin. These lesions are destructive and heal slowly, frequently leading to permanent complications like hair loss, skin atrophy, and significant scarring.
Autoimmune Basis and Environmental Triggers
The underlying mechanism of CLE involves an autoimmune response where the body’s immune cells attack healthy skin cells. This process is initiated by an interplay between an individual’s genetic predisposition and specific environmental factors. The resulting inflammation damages the cells at the dermal-epidermal junction, the boundary between the skin’s two main layers.
Ultraviolet (UV) radiation from sunlight is the primary trigger for CLE flares and lesion development across all subtypes. UV light damages skin cells, causing them to undergo programmed cell death. The immune system then misidentifies the cellular debris, generating autoantibodies that target the skin. Certain prescription medications and cigarette smoke are also environmental factors that can induce or worsen CLE in genetically susceptible individuals.
Confirming the Diagnosis
Diagnosing CLE relies on correlating clinical presentation with laboratory and histological findings, as the skin lesions can mimic other dermatological conditions like rosacea or psoriasis. A dermatologist performs a detailed clinical examination, noting the morphology and distribution of the lesions to classify the specific CLE subtype and guide subsequent diagnostic tests.
Blood tests check for specific autoantibodies, which help determine the risk of systemic involvement. Antinuclear antibodies (ANA) are often measured, and specific antibodies such as anti-Ro/SSA and anti-La/SSB are frequently associated with SCLE. Definitive confirmation of CLE is achieved through a skin biopsy. This procedure involves removing a small tissue sample for a pathologist to examine, looking for characteristic signs like interface dermatitis and lymphocytic infiltrates at the dermal-epidermal junction.
Managing Symptoms and Lesions
Management of CLE lesions centers on photoprotection and targeted pharmacological intervention. Photoprotection is the most important measure for all patients, as it directly addresses the primary environmental trigger. This involves sun avoidance, wearing UV-protective clothing, and the daily application of broad-spectrum sunscreen with a Sun Protection Factor (SPF) of 50 or higher.
Pharmacological treatments begin with topical agents for localized disease, such as high-potency corticosteroids or calcineurin inhibitors, which reduce inflammation at the lesion site. For more widespread or treatment-resistant disease, systemic therapy is necessary, with antimalarial drugs like hydroxychloroquine being the first-line choice. Antimalarials can take several weeks to reach full effectiveness, and smoking cessation is advised because nicotine metabolites reduce the drug’s efficacy. When disease is refractory to antimalarials, other systemic options, including immunosuppressants like methotrexate or mycophenolate mofetil, control the overactive immune response.
Relationship to Systemic Lupus
The risk of progression from CLE to SLE varies significantly depending on the subtype. Patients presenting with ACLE have a high likelihood of having or developing SLE, and ACLE is often a marker of active systemic disease.
Individuals with SCLE have an intermediate risk, with approximately 50% meeting the diagnostic criteria for a milder form of SLE. In contrast, patients whose disease is limited to the chronic DLE subtype have the lowest risk of systemic progression, with only about 5% to 10% developing SLE over time. This distinction determines the necessary level of monitoring and systemic workup for each patient.