A 34-year-old woman has smooth, firm, urticaria-like erythematous plaques on the face, upper back and shoulders for eight months. The plaques are photosensitive, resolve without scarring, and show no scale or follicular plugging. Biopsy shows a perivascular and periadnexal lymphocytic infiltrate with mucin deposition but minimal epidermal or interface change. Direct immunofluorescence is negative. The most likely diagnosis is:

• A Tumid lupus erythematosus ✓
• B Subacute cutaneous lupus erythematosus
• C Discoid lupus erythematosus
• D Lymphocytic infiltration of the skin (Jessner)

Explanation

Tumid lupus presents as oedematous, non-scaling, photosensitive plaques that heal without scarring. Histology shows abundant dermal mucin and a lymphocytic infiltrate with a preserved, essentially unaffected epidermis, and direct immunofluorescence is typically negative. This distinguishes it from SCLE and DLE, both of which show interface dermatitis with basement membrane damage and positive immunoreactant deposition at the dermoepidermal junction.

Reference: Rook's Textbook of Dermatology, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.