Background
Subacute cutaneous lupus erythematosus (SCLE) is a nonscarring, non–atrophy-producing, photosensitive dermatosis. SCLE commonly develops in sun-exposed areas, including the upper back, shoulders, extensor arms, neck, and upper torso, while the face is often spared. These skin lesions can appear as either papulosquamous (psoriasiform) or annular lesions.
SCLE is a subtype of cutaneous lupus erythematosus (CLE); other subtypes include acute cutaneous lupus erythematosus (ACLE) and chronic cutaneous lupus erythematosus. Chronic cutaneous lupus erythematosus includes discoid lupus erythematosus (DLE), lupus erythematous panniculitis/profundus, lupus tumidus, and chilblain lupus.
SCLE may occur in patients with systemic lupus erythematosus (SLE), Sjögren syndrome, deficiency of the second component of complement (C2d), or it may be drug-induced. SCLE is the most common subtype of CLE associated with Sjögren syndrome. [1] Some patients with SCLE may also have ACLE, if they have concomitant SLE, or the lesions of DLE and some may develop small-vessel vasculitis. (See the image below.)
Early lesions of subacute cutaneous lupus erythematosus may simulate polymorphous light eruption.
See Cutaneous Clues to Accurately Diagnosing Rheumatologic Disease, a Critical Images slideshow, to help recognize cutaneous manifestations of rheumatologic diseases.
Patients with SCLE frequently fulfill four or more of the criteria used to classify SLE. Serologic abnormalities are common. Therapy with sunscreens, topical corticosteroids, and antimalarial agents is often effective; however, some patients require additional agents to control their cutaneous disease. If SCLE is drug-induced, withdrawal of the culprit medication in conjunction with medical therapy is often necessary for disease control. (See Workup and Treatment.)
SCLE lesions heal without scarring or atrophy, but they may result in dyspigmentation, which can be prominent. Severe systemic disease is unusual, but when it occurs, the patient may develop life-altering sequelae.
Etiology
Subacute cutaneous lupus erythematosus (SCLE) occurs in genetically predisposed individuals, most often in patients with human leukocyte antigen B8 (HLA-B8), human leukocyte antigen DR3 (HLA-DR3), human leukocyte antigen DRw52 (HLA-DRw52), and human leukocyte antigen DQ1 (HLA-DQ1). A strong association exists with anti-Ro (SS-A) autoantibodies, as greater than 80% of patients with SCLE have anti-Ro (SS-A) positivity. [2] The reaction is believed to be related to ultraviolet (UV) light modulation of autoantigens, epidermal cytokines, and adhesion molecules, with resultant keratinocyte apoptosis. One study demonstrated that patients with SCLE, as well as those with discoid lupus erythematosus, but not those with lupus tumidus, have elevated levels of type I interferon-regulated genes in their blood. Furthermore, the levels were correlated with the patients' cutaneous disease activity severity levels as measured by the Cutaneous Lupus Area and Severity Index (CLASI). [3]
SCLE usually manifests following UV light exposure, but other triggers or inciting factors may also be involved given that not all patients have disease that follows photoexposure. Exacerbation of disease or induction of lesions is more common following UV-B exposure, but it can also occur in patients exposed to UV-A. Some patients exhibit sensitivity to only UV-A or to UV-A and UV-B. [4]
In perhaps as many as 30% of patients with SCLE, drugs may exacerbate or induce their disease. [5] Traditionally, hydrochlorothiazide has been the most frequently implicated drug; however, other antihypertensive agents, along with a list of over 100 different agents, have been reported in relation to the induction or exacerbation in individual patients. [6]
Additional implicated agents include calcium channel blockers, angiotensin-converting enzyme inhibitors, nonsteroidal anti-inflammatory drugs, antifungal agents (particularly terbinafine), chemotherapy agents, immunotherapies, proton pump inhibitors, and tumor necrosis factor (TNF) antagonists. [7, 8, 9, 10, 11, 12, 13, 14, 15, 16] In a 2012 population-based, matched case-control study of the incidence of SCLE cases in Sweden, the most increased odds ratios (OR) for developing SCLE from drug exposures were found with terbinafine (OR, 52.9), TNF antagonists (OR, 8.0), antiepileptics (OR, 3.4), and proton pump inhibitors (OR, 2.9). [5] Therefore, a careful drug history is a critical part of the initial evaluation of patients with SCLE. [17]
Patients with a deficiency of the second component of complement (C2d) often manifest SCLE lesions as part of their SLE-like disease.
Epidemiology
Worldwide, subacute cutaneous lupus erythematosus (SCLE) prevalence ranges from 17-48 cases per 100,000 persons. The incidence of cutaneous lupus erythematosus (CLE) is 4.3 cases per 100,000 persons and that of SCLE specifically is 0.63 case per 100,000 persons. [18] The male-to-female ratio of CLE is approximately 1:2-3. [18] The male-to-female ratio of SCLE is 1:4. Of patients with CLE, 10-50% have SCLE.
SCLE is more common in whites (>85%). The condition typically occurs in patients aged 15-70 years, with the mean age being approximately 43 years. Patients who have drug-induced SCLE may be older than those with idiopathic SCLE. [19] It is estimated that 50% of patients with SCLE meet criteria for having systemic lupus erythematosus (SLE), and approximately 10% of SLE patients have SCLE lesions.
The highest prevalence of SLE occurs in patients aged 40-60 years. The male-to-female ratio of SLE is approximately 1:10.
Prognosis
Subacute cutaneous lupus erythematosus (SCLE) uncomplicated by severe systemic lupus erythematosus (SLE) has a good prognosis. Some patients may manifest spontaneous remission; however, most have chronically active disease or a course punctuated by intermittent exacerbations. Exacerbation in the spring or summer is common. By definition, skin lesions heal without scarring or atrophy but may leave residual dyspigmentation.
Approximately half the patients with SCLE meet four or more of the criteria for classification as SLE. [20] In these patients, the systemic disease is generally mild, with arthralgia and myalgia being the most common symptoms. In a 2016 retrospective study assessing 85 patients with SCLE who fulfilled both the 1997 American College of Rheumatology (ACR) and the 2012 Systemic Lupus International Collaborating Clinics (SLICC) criteria for SLE, patients with SLCE who formally met criteria for SLE did not have more significant systemic disease when compared with SCLE-only patients. Patients with SCLE who met SLE criteria were more frequently found to have oral ulcers, a positive antinuclear antibody (ANA), positive anti-dsDNA, and low complement levels. [21] However, in up to 10% of patients, severe systemic disease, including central nervous system involvement, vasculitis, or nephritis, is possible. [22] Individuals with the papulosquamous type of SCLE may be more likely to develop renal disease. [23]
Patient Education
Instruct patients about sun-avoidance techniques, the use of sun-protective clothing, and the appropriate use of broad-spectrum sunscreens.
Because subacute cutaneous lupus erythematosus (SCLE) is exacerbated by sunlight or other UV light exposure, advise patients to take precautions. One precaution is to discourage exposure to sunlight between the hours of 10 am and 4 pm. While this is beneficial to some patients, many are so exquisitely photosensitive that this alteration does not help. In addition, advise patients to avoid artificial light sources, such as tanning beds.
Discuss the expectations for prognosis. Patients should be educated on the systemic manifestations of systemic lupus erythematosus (SLE) and be followed regularly for these.
For patient education information Lupus (Systemic Lupus Erythematosus).
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Early lesions of subacute cutaneous lupus erythematosus may simulate polymorphous light eruption.
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Papulosquamous lesions of subacute cutaneous lupus erythematosus may simulate psoriasis.
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Annular lesions of subacute cutaneous lupus erythematosus.
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Tumid lupus erythematosus.
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Neonatal lupus erythematosus.
