Subacute Cutaneous Lupus Erythematosus (SCLE) Workup

Updated: Apr 14, 2020
  • Author: Elizabeth Brezinski Wallace, MD; Chief Editor: William D James, MD  more...
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Workup

Approach Considerations

In order to ensure proper diagnosis, relevant clinical history, medication history, detailed skin and physical examinations, laboratory tests, serologic tests, and skin biopsy should be used. It is important to classify cutaneous lupus skin lesions correctly when possible and evaluate for any evidence of systemic involvement.

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Laboratory Studies

The extent of laboratory workup should be individualized and based on the level of suspicion for systemic involvement, as follows:

  • Complete blood cell (CBC) count to evaluate for hematologic abnormalities, including anemia, leukopenia, and/or thrombocytopenia

  • Renal function test and urinalysis to evaluate for evidence of proteinuria and renal insufficiency.

  • Antibody testing first with antinuclear antibody (ANA), then other autoantibodies (including but not limited to anti-dsDNA, -Ro, -La, -Sm, -ribosomal P) when systemic lupus erythematosus is suspected

  • Complement level (C3 and C4)

 

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Serologic Testing

As mentioned, most patients with subacute cutaneous lupus erythematosus (SCLE) manifest a positive antinuclear antibody (ANA) when tested with human substrates. HEp-2 cells are the substrate used most commonly in commercial laboratories. In a multicenter study, 70% of patients with SCLE were found to have positive ANA and only 5% had positive anti-dsDNA. [25] Antinative DNA (double-stranded or nDNA) antibodies usually reflect systemic lupus erythematosus (SLE).

Anti-Ro (SS-A) autoantibodies are present in a high proportion of patients, as follows:

  • Annular SCLE - 90%

  • Papulosquamous SCLE - 80-85%

  • SCLE with vasculitis, Sjögren syndrome, or C2d deficiency - Greater than 95%

  • Mothers of infants with neonatal lupus erythematosus (NLE) - Greater than 90%

  • Drug-induced SCLE - 70-80%

Anti-La (SS-B) autoantibodies are often present, but in a lower percentage of patients (typically < 50%). It is also possible to have negative ANA but positive anti-Ro antibody in SCLE patients. [21]

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Biopsy and Histologic Findings

Characteristic histopathologic alterations observed in subacute cutaneous lupus erythematosus (SCLE) include (1) vacuolar alteration of the basal cell layer and (2) an inflammatory cell infiltrate (usually lymphocytic) around vessels (perivascular), around appendiceal structures (periappendiceal), and in a subepidermal location. Epidermal changes, such as atrophy, are common, but follicular plugging is less frequent than in patients with discoid lupus erythematosus (DLE). An abundance of mucin often is seen within the dermis.

Histopathologic features differ depending on the type, site, and age of the lesion. For example, papulosquamous lesions of SCLE are much more likely to manifest diagnostic findings than are annular lesions of SCLE.

Occasionally, direct immunofluorescence (DIF) testing may aid in diagnosis. A positive lupus band test (LBT) is defined as findings of immunoglobulin and/or complement at the dermoepidermal junction. These deposits appear granular and contain IgG, IgM, and occasionally IgA. [26] Examination of tissue may be performed on skin lesions (lesional) or healthy skin (nonlesional). However, nonlesional positive LBTs can be seen in systemic lupus erythematosus (SLE), rheumatoid arthritis, Sjögren syndrome, and other autoimmune diseases. [27]

Older lesions may be more likely to be negative on immunofluorescence microscopy. The frequency of positive tests also is affected by tissue handling techniques. Snap frozen tissue is less likely to be falsely positive than tissue sent to the laboratory in Michel transport media.

In the majority of cases, clinical and histologic findings are sufficient to make the diagnosis of cutaneous lupus without the need for DIF or lupus band testing.

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