Skin Biopsy for Diagnosing Discoid Lupus Erythematosus.

Discoid lupus erythematosus (DLE) is the most common variant of cutaneous lupus erythematosus (CLE). It typically affects the scalp, face, auricle, and lips. When lesions extend beyond these areas to involve the trunk and limbs, the condition is termed disseminated DLE (DDLE). The pathognomonic skin lesions present as well-demarcated discoid erythematous plaques with firmly adherent scales or crusts, central atrophy, characteristic scarring, and pigmentary changes, potentially leading to irreversible scarring alopecia. Histopathological and immunopathological examination of the skin lesions is instrumental in diagnosing DLE. Histologically, DLE is characterized by hyperkeratosis, follicular plugging, focal epidermal thinning, vacuolar alteration of the dermo-epidermal interface, thickening of the epidermal basement membrane, and a superficial and deep perivascular and periadnexal lymphocytic infiltrate, often in conjunction with interstitial mucin. Direct immunofluorescence (DIF) may reveal deposits of immunoglobulins and complement at the dermo-epidermal junction (DEJ). The following article outlines the protocols for DLE lesion assessment, skin biopsy procedures, histopathological and immunopathological analysis, and management options, with the aim of providing a comprehensive, standardized, and replicable diagnostic and therapeutic process to assist clinical physicians in practice.