DLE is different from systemic lupus erythematosus, a connective-tissue disease that affects many different organs. Discoid lupus progresses to systemic lupus in about 1 in 20 persons. The peak incidence occurs in women in their late 20s. Plaques are 1cm to 4cm in diameter and have clearly defined borders. They may appear anywhere on the face, but the cheeks and jawline are the most common sites.
Lesions sometimes appear on the scalp with localized patches of hair loss.
Lesions scar as they heal. Protection from sunlight decreases the severity. Your own observation of symptoms. Medical history and physical exam by a doctor. Laboratory blood studies and biopsy of skin lesions to rule out systemic lupus erythematosus.