Guillain-Barré Syndrome with transient syphilis seropositivity: A case report

While confirmatory syphilis tests are highly specific, conflicting or transient results, as seen in this case, can pose significant diagnostic challenges. This report details the case of a 43-year-old female diagnosed with Guillain-Barré Syndrome (GBS) who subsequently exhibited transient serological reactivity for syphilis following intravenous immunoglobulin (IVIG) therapy. The patient presented with acute progressive weakness consistent with GBS, for which she received a five-day course of IVIG, leading to complete clinical recovery. Post-IVIG, screening revealed a weakly reactive Venereal Disease Research Laboratory (VDRL) test and a positive Treponema pallidum particle agglutination (TPPA) test. Subsequent repeat testing showed a non-reactive VDRL but persistently positive TPPA, followed by complete seroreversion of both tests two months later, confirming the absence of syphilis. This case underscores the crucial need for cautious interpretation of syphilis serology in patients who have recently received IVIG, highlighting the potential for false-positive results due to passive antibody transfer and emphasizing the importance of clinical correlation and serial testing to prevent misdiagnosis and unnecessary treatment.