Discoid lupus erythematosus (DLE) is a chronic cutaneous form of lupus characterized by erythematous lesions, dyspigmentation, and scarring that may progress to systemic lupus erythematosus (SLE). This systematic review analyzed epidemiology, clinical patterns, immunologic features, progression rates, and treatment outcomes in 2,814 patients across 72 studies, including 626 pediatric/neonatal and 2,188 adult cases. Female participants predominated in both groups (68.5% in pediatrics; 74.2% in adults), with a higher prevalence among African/African American patients (29.6% in pediatrics and 33.8% in adults). The mean age at diagnosis was 11 years in children and 34 years in adults. Localized lesions were most common in pediatric patients (61.3%) and adult patients (58.7%). Progression to SLE occurred in 30.0% of pediatric cases and 25.4% of adults. Identified risk factors included early-onset disease (in children, <10 years; in adults, <20 years), ANA positivity (51% in pediatric; 48% in adult), high ANA titers (≥1:320), and a family history of rheumatic disease. Treatment relied mainly on topical corticosteroids (44.4% pediatric; 51.6% adult) and hydroxychloroquine (11.1% pediatric; 28.7% adult), while newer therapies such as lenalidomide and anifrolumab showed potential benefits. Overall, DLE demonstrates a strong female predominance and a substantial likelihood of progression to SLE, particularly in younger patients with autoantibody positivity.