SCLE

Subacute Cutaneous Lupus Erythematosus (SCLE)

Key Points

• SCLE is a subtype of cutaneous lupus erythematosus characterized by:

  • Photosensitive lesions on sun-exposed skin.

  • Lesions typically annular or papulosquamous, resolving without scarring (though dyspigmentation may result).

  • Association with anti-SSA/Ro autoantibodies.

  • Minimal serious systemic involvement; some patients may develop systemic lupus erythematosus (SLE).

  • Drug-induced SCLE is a consideration; several medications implicated.

• Lesions predominantly appear on:

  • Sides of the face

  • Upper trunk

  • Extensor surfaces of the upper extremities

  • Midface usually spared.

Epidemiology

• Specific epidemiological data for SCLE alone is limited.

• SLE, associated with SCLE, is more common in women, particularly during childbearing years.

• Higher prevalence in African-American women, often presenting earlier.

Pathogenesis

• Involves an interaction between genetic and environmental factors:

  • Environmental triggers include: UV radiation, medications, cigarette smoking, potential viral influences.

  • UV radiation induces apoptosis, facilitating the release of antigens and increasing keratinocyte production of SSA/Ro52 and type I interferons.

  • Inflammatory cytokines stimulated by UVR include TNF, IL-1, IFN-γ, and others.

  • Mechanistic cascade:

    • Activation of dendritic cells

    • Release of interferon

    • T cell activation

    • Chemokine production

  • The lichenoid tissue reaction is a hallmark of cutaneous lupus.

  • Anti-SSA/Ro autoantibodies are crucial in SCLE's pathogenesis.

Rash Description and Clinical Features

• Photosensitivity is commonly observed.

• Lesion morphology:

  • Annular plaques with raised borders and central clearing

  • Papulosquamous eruptions.

• Commonly affected areas exclude midface, affecting:

  • Sides of face

  • Upper trunk

  • Extensor aspects of upper extremities.

• Lesions are minimally palpable, with sparse inflammatory infiltrate, often leading to:

  • Dyspigmentation (often hypopigmentation)

  • Rarely scarring or dermal atrophy.

Diagnostic Criteria

• Defined by:

  • Non-indurated psoriasiform or annular polycyclic lesions that resolve without scarring (dyspigmentation may occur).

• Noted in both 2012 SLICC and 2019 EULAR/ACR classification systems.

Diagnosis and Investigations

• Lesional Biopsy:

  • H&E staining reveals mild interface dermatitis, sparse superficial lymphoid infiltrate, and possible apoptotic keratinocytes.

  • Minimal hyperkeratosis and no deep dermal infiltrate.

• Direct Immunofluorescence (DIF):

  • Often positive in active lesions with granular deposits of IgG and/or IgM in the epidermis.

• Systemic Evaluation:

  • Directed history, physical exam, lab tests including ANA profile, urinalysis, CBC, chemistries, ESR, CRP, complement levels.

Differential Diagnosis

• Psoriasis

• Dermatophytosis

• Photolichenoid drug eruption

• Polymorphous light eruption

• Granuloma annulare

• Figurate erythemas, dermatitis, pemphigus foliaceus.

Treatment/Management

• Topical Therapy:

  • Topical corticosteroids are primary therapy.

• Systemic Therapy:

  • Antimalarials (hydroxychloroquine) considered the gold standard.

• Adjunctive Therapy:

  • Essential sun protection.

  • Smoking cessation.

  • Avoidance of photosensitizing medications.

Complications

• Possible dyspigmentation.

• Risk of progressing to systemic lupus erythematosus (SLE).

• Severe variants may include toxic epidermal necrolysis-like eruptions.

Additional Notes

• The three cutaneous lupus types (ACLE, SCLE, DLE) may coexist.

• SCLE may exhibit a chronic, relapsing nature.