Lupus erythematosus is a heterogeneous connective-tissue disease associated with polyclonal B-cell activation and is believed to result from the interplay of genetic, environmental, and hormonal factors. The spectrum of disease involvement can vary from limited cutaneous involvement to devastating systemic disease. (See Etiology.)
From a dermatologic standpoint, the type of skin involvement can prove to be a good barometer of the pattern of underlying systemic activity. Lupus erythematosus–specific skin diseases are recognized in 3 categories, including (1) acute cutaneous lupus erythematosus (ACLE), (2) subacute cutaneous lupus erythematosus (SCLE), and (3) chronic cutaneous lupus erythematosus (CCLE). (See the diagram below.) Clinical characteristics of each group are unique, although histopathologically, only subtle differences are identified. The focus of this article is on acute cutaneous lupus erythematosus. [1, 2] (See Etiology, History, Physical Examination, and Workup.)
See Cutaneous Clues to Accurately Diagnosing Rheumatologic Disease, a Critical Images slideshow, to help recognize cutaneous manifestations of rheumatologic diseases.
Acute cutaneous lupus erythematosus refers to a typical malar eruption in a butterfly pattern localized to the central portion of the face and/or a more generalized maculopapular eruption representing a photosensitive dermatitis. (See the image below.) The condition has a strong association with the systemic disease for which patients present to rheumatologists and internists. (See History and Physical Examination.)
Acute cutaneous lupus erythematosus can be transient, lasting for several days to weeks. Lesions wax and wane with sun exposure over a period of several hours; however, some patients experience prolonged disease activity.
Resolution of lesions may result in postinflammatory hyperpigmentation, especially in patients with darkly pigmented skin. Usually, the lesions are nonscarring. (See Prognosis, History, and Physical Examination.)
Educate patients about the nature of skin, which acts as a barometer of disease activity. Control of the cutaneous manifestations depends ultimately on overall control of the disease. Instruct patients regarding the effects of ultraviolet light in exacerbating the disease.
The etiology of lupus erythematosus is believed to be multifactorial, involving genetic, environmental, and hormonal factors. An association with human leukocyte antigen DR2 and human leukocyte antigen DR3 has been identified. Concordance in monozygotic twins and familial associations support a genetic basis in acute cutaneous lupus erythematosus.
More than 25 genes have been identified as contributing to the mechanisms that predispose patients to lupus. They include alleles in the major histocompatibility complex region (multiple genes): IRF5, ITGAM, STAT4, BLK, BANK1, PDCD1, PTPN22, TNFSF4, TNFA1P3, SPP1, some fc gene receptors, and deficiency in several complement components, including C1qC4+C2.
In patients who are predisposed genetically, exposure to natural ultraviolet radiation is a frequent precipitating factor for lupus erythematosus. In addition, certain viruses (eg, Epstein-Barr virus, cytomegalovirus, human immunodeficiency virus [HIV]) have been implicated in precipitating or exacerbating lupus erythematosus in genetically predisposed individuals.
Chemicals such as L-canavanine, which is present in alfalfa sprouts, have been known to induce systemic lupus erythematosus–like illness. Drugs implicated in inducing a lupus erythematosus–like illness (eg, procainamide, isoniazid, hydralazine) typically do not induce acute cutaneous lupus erythematosus.
Data concerning direct immunofluorescence in acute cutaneous lupus erythematosus are sparse. In one study, the results of 5 (100%) of 5 skin biopsy specimens were reported as positive for the lupus band test. The lupus band test reveals the presence of immunoglobulins and C3 complement components along the dermoepidermal junction. All 3 immunoglobulin classes (immunoglobulin G [IgG], IgM, IgA) and a variety of complement components have been identified at the dermoepidermal junction.
Research has shown that 60% of patients with a malar eruption of lupus erythematosus have positive lupus band test results. In nonlesional skin, positive lupus band test results correlate strongly with an aggressive course of systemic disease.
In the United States, the malar rash has been reported in 20-60% of patients in large lupus erythematosus cohorts, while limited data suggest that the maculopapular eruption is present in 35% of patients with systemic lupus erythematosus. The malar rash is believed to be associated with a younger age of disease onset.
Precise data concerning the prevalence of acute cutaneous lupus erythematosus in specific racial groups are not available; however, since photosensitivity is observed more frequently in whites than in blacks, the same prevalence of acute cutaneous lupus erythematosus may be inferred. Estimates suggest that 1 in 250 black women in the United States and the Caribbean and 1 in 1000 Chinese persons have systemic lupus erythematosus. Although lupus erythematosus may be rare in most parts of Africa, data concerning this finding conflict.
Data concerning acute cutaneous lupus erythematosus are difficult to interpret, since a lack of conformity is found in the description of lesions, and biopsy data are lacking for skin lesions observed in patients with systemic disease.
Significant morbidity and potential mortality are associated with systemic lupus erythematosus, of which acute cutaneous lupus erythematosus is a manifestation.
The malar eruption tends to wax and wane with systemic activity; however, whether the presence of malar rash indicates a worse overall outlook for patients has not been determined. Progression to lupus erythematosus–specific bullous dermatosis (aggravated by sun exposure) may occur, producing a toxic epidermal necrolysis (TEN) ̶ type picture.
No definite correlation has been identified between acute cutaneous lupus erythematosus and nephritis; however, localized lesions of acute cutaneous lupus erythematosus are believed to tend to wax and wane, paralleling the underlying systemic disease. Postinflammatory hyperpigmentation may occur in dark-skinned patients following resolution.
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