Discoid Lupus Erythematosus Workup

Updated: Jun 11, 2020
  • Author: Ruth Ann Vleugels, MD, MPH; Chief Editor: William D James, MD  more...
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Workup

Approach Considerations

Screening for systemic lupus erythematosus (SLE) should occur upon diagnosis of discoid lupus erythematosus (DLE). This should consist of a thorough history and physical examination, as well as standard laboratory screening including complete blood cell count, renal function tests, and urinalysis. Hematologic and serologic abnormalities may be present and an elevated sedimentation rate may occur in some patients. Additionally, rheumatoid factor may be positive and complement levels may be decreased. Abnormal renal function tests and/or urinalysis with proteinuria may reflect the presence of renal involvement.

Some patients with DLE (approximately 20%) manifest a positive antinuclear antibody (ANA) when tested with human substrates. HEp-2 cells currently are the most common substrate used in commercial laboratories.

Anti-Ro (SS-A) autoantibodies are present in up to 20% of patients. Antinative deoxyribonucleic acid (DNA, either double-stranded or nDNA) or anti-Sm antibodies usually reflect SLE, and they may occur in some patients (5-20%). [25] In one study, levels of ANA, anti-RNP, anti-dsDNA, and anti-ssDNA IgG were associated with disease activity of DLE as determined by the Cutaneous Lupus Disease Area and Severity Index (CLASI). [26]

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Other Tests

Deposition of immunoglobulin and/or complement at the dermoepidermal junction is a characteristic feature of lupus erythematosus. Tissue may be examined from skin lesions (lesional) or normal skin (nonlesional). Nonlesional biopsies may be from photoexposed or nonexposed surfaces. Testing of nonlesional, nonexposed skin is termed the lupus band test (LBT).

The use and interpretation of these tests vary according to the biopsy site. Approximately 90% of patients with discoid lupus erythematosus (DLE) manifest a positive direct immunofluorescence (DIF) test on lesional skin; however, the presence of immunoreactants in the basement membrane zone of lesional skin is not specific for lupus and can be seen in a variety of inflammatory skin diseases. Older lesions or very early lesions may be more likely to be negative on immunofluorescence microscopy. Most commonly, DLE may be diagnosed by clinical examination and histopathologic findings, rather than relying on DIF testing.

Only patients with systemic lupus erythematosus (SLE) have a positive LBT, defined as the presence of multiple immunoreactants in the basement membrane zone. The LBT is neither sensitive nor specific and has mostly been replaced by advances in serologic testing.

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Histologic Findings

The characteristic histopathologic alterations observed in discoid lupus erythematosus (DLE) include the following:

  • Vacuolar alteration of the basal cell layer

  • Thickening of the basement membrane

  • Follicular plugging

  • Hyperkeratosis

  • Atrophy of the epidermis

  • Incontinence of pigment

  • Inflammatory cell infiltrate (usually lymphocytic) in a perivascular, periappendageal, and subepidermal location

Often, an abundance of mucin is seen within the dermis. The histopathologic features differ depending on the type and age of the lesion.

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