False-Positive Syphilis Serology Leading to the Diagnosis of Systemic Lupus Erythematosus: A Case Report

We describe a case of systemic lupus erythematosus (SLE) that was initially misdiagnosed as syphilis because both non-treponemal and treponemal serological tests were positive. A 16-year-old female presented with lymphadenopathy and was treated for syphilis. However, further evaluation revealed highly active SLE with neuropsychiatric and renal involvement. The syphilis serology results converted to negative following immunosuppressive therapy. This case highlights an important diagnostic pitfall: in patients with suspected autoimmune diseases, both non-treponemal and treponemal tests may yield false-positive results, and syphilis serology should therefore be interpreted in conjunction with the clinical findings and disease context.