Based on a chronic recurrent autoimmune skin disorder with sun exposure preceding lesions, IgG and IgM deposition in the skin, and female predominance with onset in the 30s, which diagnosis is most likely?

• A. Psoriasis
• B. Discoid lupus
• C. Eczema
• D. Scleroderma

Answer: (B)

Sun exposure triggering chronic, recurrent skin plaques with immune deposits at the dermal-epidermal junction is classic for cutaneous lupus erythematosus. Discoid lupus erythematosus, the chronic skin-limited form, typically presents in women around the 30s with well-defined, coin-shaped, scaly plaques on sun-exposed areas that can scar or atrophy over time. The finding of IgG and IgM deposition along the basement membrane (the lupus band) on immunofluorescence strongly supports lupus rather than other skin conditions. Psoriasis would more likely show silvery scales and a different pattern of immune involvement without the characteristic lupus band. Eczema describes pruritic, moist/erythematous lesions without this immunofluorescence pattern, and scleroderma presents with diffuse skin thickening rather than discrete discoid plaques.