Systemic Lupus Erythematosus (SLE) is an autoimmune condition where the body’s immune system mistakenly attacks its own healthy tissues, leading to widespread inflammation. Skin involvement is a frequent and highly visible symptom of lupus, often the first sign of the disease in about one-third of cases. A dermatologist can diagnose lupus; these specialists in skin, hair, and nail conditions are often the first to recognize the characteristic signs and are instrumental in both initial diagnosis and ongoing care.
The Spectrum of Lupus Skin Manifestations
Lupus affects the skin in numerous ways, categorized into acute, subacute, and chronic cutaneous forms. Acute cutaneous lupus erythematosus (ACLE) is recognized by the malar rash, a flat or slightly raised redness across the cheeks and bridge of the nose that spares the nasal folds, creating a distinct “butterfly” pattern. This rash frequently appears during a systemic flare and resolves without leaving scars.
Subacute cutaneous lupus erythematosus (SCLE) manifests as sun-sensitive rashes on the upper back, chest, and arms, often presenting as red, scaly patches or ring-shaped lesions. While these lesions usually do not scar, they can leave behind areas of lighter or darker skin pigmentation.
Chronic cutaneous lupus is dominated by discoid lupus erythematosus (DLE), which causes thick, coin-shaped plaques most often on the face, scalp, and ears. DLE lesions are prone to causing permanent scarring and hair loss due to the deep tissue damage they inflict.
Non-Specific Skin Findings
Non-specific findings may also point toward the disease. These include a lacy, purplish pattern on the skin called livedo reticularis, caused by changes in small blood vessels. Patients may also experience Raynaud’s phenomenon, where the fingers and toes turn white or blue in response to cold or stress due to poor blood flow. Other signs include ulcers inside the mouth or nose and inflammation of the blood vessels in the skin, known as cutaneous vasculitis.
The Dermatologist’s Role in Diagnosis
The diagnostic process begins with a detailed physical examination, as the dermatologist is highly skilled at recognizing the subtle patterns of lupus lesions that can mimic other conditions like rosacea or psoriasis. Pattern recognition is especially important because the skin findings, such as the malar rash or discoid lesions, are themselves official criteria used in the overall classification of lupus. A thorough examination includes checking sun-exposed areas and looking for non-visible signs like oral ulcers or hair thinning.
To confirm the diagnosis and distinguish lupus from other inflammatory skin diseases, the dermatologist relies heavily on a skin biopsy. A punch biopsy is typically performed under local anesthesia to remove a small, deep sample of affected skin tissue for lab analysis. The tissue is studied using standard histopathology to identify characteristic changes in the skin layers and is also used for direct immunofluorescence (DIF), or the lupus band test.
DIF detects the presence of immune complexes, specifically deposits of antibodies and complement proteins, along the basement membrane zone of the skin. A positive DIF test is a strong indicator of lupus, though it is not used as a standalone diagnostic tool. The dermatologist will also order initial screening blood work, such as the Antinuclear Antibody (ANA) test, which checks for autoantibodies commonly present in lupus. While a positive ANA is not specific to lupus, a negative result makes the diagnosis less likely, providing an important piece of the clinical puzzle.
Distinguishing Cutaneous Lupus from Systemic Lupus
A central part of the dermatologist’s role is classifying the patient’s condition, determining whether the disease is confined to the skin or if it affects internal organs. This distinction separates Cutaneous Lupus Erythematosus (CLE) from Systemic Lupus Erythematosus (SLE). CLE is a form of the disease that primarily or exclusively impacts the skin, meaning internal organs like the kidneys, heart, or lungs are not involved.
When classified as CLE, the disease is often managed solely by the dermatologist with the goal of preventing scarring and controlling skin inflammation. However, the presence of specific skin subtypes, particularly ACLE, is highly suggestive of underlying or concurrent SLE. Nearly all patients with ACLE, for example, will have a positive ANA result and often have active systemic disease.
Patients should understand that a CLE diagnosis does not automatically mean they have SLE, but there is a possibility of progression. For instance, a small percentage of people initially diagnosed with DLE may eventually develop systemic involvement. The dermatologist uses clinical presentation, the specific type of rash, and laboratory findings to assess the overall risk and determine the appropriate classification for the patient’s long-term care.
Collaborative Treatment and Management
Once a diagnosis is established, the dermatologist manages skin symptoms and works to prevent irreversible damage like scarring and permanent hair loss. Localized CLE lesions are often treated with high-potency topical corticosteroids or calcineurin inhibitors, which are applied directly to the affected skin to reduce inflammation. For thick or resistant lesions, the dermatologist may perform intralesional injections of corticosteroids directly into the plaque.
For more widespread cutaneous disease or for patients with SLE, systemic medications are introduced. Antimalarials such as hydroxychloroquine are the preferred first-line treatment, effective for both skin and systemic symptoms, helping to reduce the frequency of disease flares. The use of these systemic drugs necessitates coordination with other specialists for monitoring potential side effects.
When SLE is confirmed or strongly suspected, the dermatologist makes a prompt referral to a rheumatologist. The rheumatologist specializes in autoimmune and inflammatory diseases affecting the joints and internal organs, managing the systemic aspects of the disease. Effective care for lupus often involves this multidisciplinary approach, with dermatologists and rheumatologists working together to provide comprehensive treatment.