Biopsy features of DLE include vacuolar interface dermatitis, basement membrane zone thickening, follicular plugging, superficial and deep perivascular and periadnexal lymphohistiocytic inflammation with plasma cells, and increased mucin deposition. Direct immunofluorescence biopsy may show a continuous granular immunoglobulin (Ig) G/IgA/IgM and C3 band at the basement membrane zone.
Abnormal serologic tests may support the diagnosis of SLE based on American College of Rheumatology criteria and could suggest additional organ involvement or associated conditions, such as lupus nephritis or antiphospholipid syndrome (respectively). Currently, no clear consensus exists on monitoring patients with cutaneous lupus for systemic disease.
A gamut of skin-changing conditions should be considered
The differential diagnosis in this case includes SCLE, dermatitis, tinea corporis, cutaneous drug eruptions, and graft-versus-host disease (GVHD).
SCLE classically manifests with annular or psoriasiform lesions on the sun-exposed areas of the upper trunk (eg, the chest, neck, and upper extremities), while the central face and scalp are typically spared. Differentiating between generalized DLE and SCLE may be the most difficult, given similarities in the associated skin changes.
Dermatitis (atopic or contact) manifests as pruritic erythematous eczematous plaques, most commonly involving the flexural areas in atopic dermatitis and an exposure-dependent distribution pattern in contact dermatitis. The patient may have a history of atopy.
Continue to: Tinea corporis