Dr Helen Gordon, Dermatology Registrar, Greenlane Hospital, Auckland, New Zealand. DermNet NZ Editor in Chief: Adjunct A/Prof. Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. July 2019.
SCLE affects about 10% of all lupus patients.
SCLE is due to genetic and environmental factors.
SCLE is associated with a group of alleles called the Human Leukocyte Antigen (HLA)-A1, B8, DR3, DQ2, DRw52, C4null ancestral haplotypes. Other genetic associations include:
Exposure to UV results in increased expression of the Ro/SS-A antigen on the surface of keratinocytes, binding the antibody and leading to the disease.
Up to 65% of cases of SCLE are drug-induced. The incubation time widely varies from a few days (such as in chemotherapy agents capecitabine and paclitaxel) to years before the onset of the rash (eg, a case was reported to arise five years after starting a thiazide diuretic).
The drugs most commonly associated with SCLE are:
Other drugs which may cause SCLE include:
SCLE most often presents as a non-scarring papulosquamous eruption.
Other lupus-associated findings in patients with SLCE include:
Drug-induced lupus can be indistinguishable from the non-drug induced form of SCLE. Specific features of drug-induced SCLE include:
Around 50% of patients with SCLE meet the American College of Rheumatology criteria for the diagnosis of systemic lupus erythematosus (SLE).
A pregnant woman who are Ro/SS-A antibody positive has a risk of delivering an infant suffering from neonatal lupus erythematosus (8–10%) and congenital heart block (1–2%).
SCLE can be diagnosed clinically, supported by the results of blood tests and a skin biopsy.
Histology on biopsy can resemble other forms of cutaneous lupus.
Drug-induced SCLE and non-drug induced SCLE cannot be distinguished on histology.
Differentials include other types of cutaneous lupus:
Other skin conditions that may be considered include:
Sun protection is crucial.
Topical therapy may include:
In approximately 25% of cases, another agent is required, such as:
SCLE generally responds well to treatment, although it may flare up again each summer.
Approximately 10–15% of patients with SCLE develop SLE, including renal and neurological involvement.
Drug-induced SCLE can be slow to resolve on stopping the causative drug (one study found resolution took a mean of 7 weeks).
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