Malar rash in systemic lupus erythematosus: clinical, serological, and therapeutic associations in a single-center retrospective study of 1039 patients.

INTRODUCTION: Malar rash is a hallmark manifestation of systemic lupus erythematosus (SLE); however, its clinical and immunological significance remains incompletely understood. OBJECTIVES: To investigate the associations of malar rash with clinical phenotype, serological profile, comorbidities, and treatment patterns in SLE. PATIENTS AND METHODS: We retrospectively analyzed 1039 patients with SLE who fulfilled the 2019 EULAR/ACR classification criteria and were treated at a tertiary referral center between 2012 and 2022. Patients were stratified according to the presence or absence of malar rash. RESULTS: Malar rash was present in 444 patients (42.7%). Patients with malar rash had an earlier disease onset (32 vs 37 years) and a longer disease duration (14 vs 11 years; both P <0.001). Constitutional symptoms were more frequent in patients with malar rash (81.8% vs 73.2%, P = 0.001), including fever, fatigue, myalgia, and weight loss. Mucocutaneous and musculoskeletal manifestations were also more common in this group (all P <0.001). Leukopenia occurred more frequently in patients with malar rash, whereas hemolytic anemia was more common in those without malar rash. Pulmonary involvement was less frequent in patients with malar rash, while renal and neurological manifestations did not differ significantly between the groups. Anti-Sm and anti-RNP antibodies were more frequently detected in patients with malar rash. Patients with malar rash were also more likely to receive antimalarial agents and azathioprine. CONCLUSIONS: Malar rash is associated with an earlier SLE onset and a distinct clinical phenotype characterized by increased constitutional, mucocutaneous, and musculoskeletal involvement, specific serological features, and less frequent pulmonary manifestations.