STOWE, VT. — Skin involvement is one of the most frequent manifestations of lupus erythematosus, yet the cutaneous signs of the disease are not always recognized, Dr. Victoria P. Werth said at a dermatology conference sponsored by the University of Vermont.
The diagnostic challenge is recognizing these cutaneous conditions, particularly because they encompass as many as 15 different clinical presentations, said Dr. Werth of the University of Pennsylvania, Philadelphia.
It's important to know what to look for, “not only so we can treat the skin problems, but also so we can identify signs of systemic disease when they occur,” she said.
Although systemic lupus erythematosus (SLE) is estimated to occur in 17–48 per 100,000 individuals, the cutaneous variants are thought to be two to three times more prevalent.
Skin findings in cutaneous lupus are generally categorized into lupus-specific and lupus-nonspecific diseases, based on biopsy findings.
“Lupus-specific lesions show histology that is specific to lupus erythematosus, while nonspecific lesions are not histopathologically distinct for the disease and may be seen as a feature of another disease process,” Dr. Werth explained. Some of the more common nonspecific skin findings include alopecia, vasculitis, and Raynaud's phenomenon.
Although skin disease is the second-most frequent clinical manifestation of SLE, cutaneous lupus does not always meet all the American College of Rheumatology's diagnostic criteria for SLE.
Lupus-specific cutaneous lesions are further subdivided into three categories: acute, subacute, and chronic. “The most recognizable acute presentation is the butterfly rash, which comes on abruptly and heals within hours or days, usually without scarring,” Dr. Werth said. Some variations of this rash include bullous formations or blisters.
Subacute manifestations can include annular and/or psoriasiform rashes that are usually highly photosensitive. Chronic cutaneous lupus is “the wastebasket category” for many of the other lupus-specific skin presentations, she said.
The most common chronic cutaneous form is discoid lupus erythematosus, which begins with well-defined scaly lesions that evolve into scarring plaques and often includes follicular involvement that can lead to hair loss.
“Early, aggressive treatment for these patients is important in order to prevent permanent, disfiguring scarring and permanent hair loss,” said Dr. Werth.
She also discussed several of the following less prevalent manifestations of chronic cutaneous lupus:
▸ Chilblain lupus. Associated with itching, cold, and painful swelling of the extremities and toes.
▸ Hypertrophic lupus. Characterized by wartlike bumps.
▸ Lupus profundus. Causes deep dermal nodules on the upper arms and sometimes on the head, chest, or legs.
▸ Lupus tumidus. Presents as broad, indurated plaques.
Because some of these conditions can mimic other skin conditions, “serologic and histologic examinations are critical for confirming a diagnosis,” Dr. Werth said.
Although management for the various lupus subsets does not differ substantially, the clinical distinctions are important because they relate to the likelihood that an individual patient will develop systemic disease, Dr. Werth pointed out.
Nearly all patients with acute cutaneous lupus, and half of those with subacute disease, will meet American College of Rheumatology criteria for SLE. With respect to chronic cutaneous lupus, those with generalized discoid lesions have a 20% chance of developing SLE, those with lupus profundus are estimated to have a 10% chance, those with localized discoid lesions have a 5% chance, and those with lupus tumidus have virtually no chance.
“Patients whose skin conditions put them at higher risk should be followed more closely for evidence of systemic disease,” she said.
Once a diagnosis of cutaneous lupus has been made, the next step is to evaluate the patient for signs of systemic disease. The initial evaluation should include history, physical examination, CBC, sedimentation rate, antinuclear antibody (ANA) testing, and urinalysis. For ANA-positive patients or ANA-negative patients in whom there is suspicion of SLE, Dr. Werth suggests a panel that includes anti-Sjouml;gren's syndrome A, anti-Sjouml;gren's syndrome B, anti-ribonucleoprotein, anti-double-stranded DNA, and anti-Smith antibodies, as well as complement studies.
Patients with positive findings warrant closer monitoring, “especially those with high titer, anti-double-stranded DNA antibody because of an increased risk for renal problems,” she said.
In terms of management, “the first order of business is advising patients to avoid precipitating factors such as heat, certain medications, and sunlight,” Dr. Werth said. “I tell my patients they should not go outside without a sunscreen that has a UVB of 30 or more, as well as a UVA blocker, like Parsol 1789.”
Patients also should avoid drugs that cause subacute lupus-like eruptions, such as thiazides, griseofulvin, terbinafine, calcium channel blockers, and ACE inhibitors, Dr. Werth noted.
In addition to preventive efforts, standard therapies include topical and sometimes intralesional corticosteroids and antimalarial drugs.