Discoid lupus erythematosus as it relates to cutaneous squamous cell carcinoma and to photosensitivity.

Lupus erythematosus is a chronic inflammatory autoimmune disease with diverse clinical manifestations ranging from an indolent chronic cutaneous form to a severe potentially life-threatening disease, systemic lupus erythematosus. Discoid lupus erythematosus is a subphenotype of chronic cutaneous lupus erythematosus, characterised by scaly disk-shaped plaques which may be localised or widespread, occurring predominantly on sun-exposed skin and which may rarely progress to squamous cell carcinoma. The pathogenesis of discoid LE comprises complex interactions between multiple susceptibility genes involved in immune responses and clearance of apoptotic cells on the one hand, and environmental factors on the other. Herein, we discuss some aspects of the pathogenesis of discoid lupus erythematosus in relation to ultraviolet radiation and malignant transformation.