Bullous Systemic Lupus Erythematosus (BSLE) Workup

Updated: Mar 13, 2018
  • Author: Sarah Sweeney Pinney, MD, FAAD; Chief Editor: Dirk M Elston, MD  more...
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Workup

Approach Considerations

Bullous systemic lupus erythematosus occurs in the setting of systemic lupus erythematosus; thus, ANA test results generally are positive. Anti-dsDNA, anti-Sm, anti-Ro/SS-A, anti-La/SS-B, and anticardiolipin antibodies may also be detected.

Other laboratory abnormalities related to systemic lupus erythematosus can include low levels of complement (ie, C3, C4, CH50), anemia, leukopenia, thrombocytopenia, proteinuria or cellular casts upon urinalysis, and an elevated erythrocyte sedimentation rate. (See also Systemic Lupus Erythematosus and Lupus Nephritis.)

Laboratory findings in persons with toxic epidermal necrolysis–like lupus erythematosus vary depending on the underlying type of lupus erythematosus present.

Although the lupus erythematosus patients with erythema multiforme–like skin lesions who were originally described by Rowell and colleagues had immunologic features that included a speckled pattern of ANAs, anti-Ro/SS-A and/or La/SS-B antibodies, and a positive rheumatoid factor, these findings are not consistently observed in lupus erythematosus patients with this clinical presentation. Anticardiolipin antibodies and lupus anticoagulant have also been reported in individuals with Rowell syndrome.

Procedures

Diagnosis of bullous systemic lupus erythematosus requires skin biopsy specimens for routine light microscopy (preferably from the edge of a fresh blister, including adjacent, clinically unblistered skin) and DIF microscopy (from perilesional skin).

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Histologic Findings

Light microscopy

Histologically, bullous systemic lupus erythematosus is characterized by dermoepidermal separation beneath an intact epidermis. A predominantly neutrophilic infiltrate is observed in an edematous upper dermis, either concentrated in the dermal papillae (similar to dermatitis herpetiformis) or distributed in a continuous band beneath the BMZ (similar to linear IgA bullous dermatosis).

Nuclear dust is often apparent, and a variable number of eosinophils and mononuclear cells are present within the dermal infiltrate. Basal keratinocyte vacuolization and other histologic features of cutaneous lupus erythematosus are typically absent.

Immunofluorescence microscopy

DIF microscopy of perilesional skin reveals deposition of IgG (with and without IgM and IgA) and complement in a linear or granular bandlike pattern at the BMZ. [4]

In type 1 bullous systemic lupus erythematosus, DIF of salt-split perilesional skin and/or IIF microscopy following incubation of the patient's serum with salt-split normal human skin reveals immunoglobulin deposits localized to the dermal floor of the split. [32] Immunoblot and immunoprecipitation studies using the patient's serum can confirm that these antibodies recognize the 290- and 145-kd proteins of type VII collagen. An enzyme-linked immunosorbent assay (ELISA) test for rapid detection of anti–type VII collagen NC1 domain antibodies has also been developed.

In addition, direct immunoelectron microscopy can be used to demonstrate that the immunoglobulin deposits are codistributed with anchoring fibrils/type VII collagen within and just below the lamina densa.

Cases with negative IIF and an undetermined sublocalization of anti-BMZ antibodies (or antibodies recognizing a dermal antigen other than collagen VII) are referred to as type 2 bullous systemic lupus erythematosus. Of note, circulating antibodies to type VII collagen are less likely to be present in patients with a granular pattern of fluorescence on DIF. Bullous systemic lupus erythematosus characterized by immunoglobulin binding the epidermal roof (type 3 bullous systemic lupus erythematosus) or the roof and the dermal floor of salt-split skin has also been observed. Antigens in such patients have included bullous pemphigoid antigen 1, laminin-5, and laminin-6.

Histologic findings in toxic epidermal necrolysis–like and erythema multiforme–like lupus erythematosus lesions

The histologic features of toxic epidermal necrolysis–like lupus erythematosus consist of full-thickness epidermal necrosis and a sparse lymphocytic infiltrate in the upper dermis, as are seen in drug-induced toxic epidermal necrolysis.

Rowell syndrome is characterized by a vacuolar interface dermatitis with lymphocyte exocytosis; prominent necrotic keratinocytes in all layers of the epidermis; a mild, superficial, perivascular lymphocytic infiltrate; and dermal edema, features suggestive of erythema multiforme but also compatible with early, hyperacute cutaneous lupus erythematosus. DIF findings are usually negative.

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