IVIg-induced false positive hepatitis B serology in a patient with <i>Guillain-Barré</i> syndrome: a case report

We report the case of a 63-year-old Moroccan male with Guillain-Barré syndrome (GBS) who, following treatment with intravenous immunoglobulin (IVIg), developed false-positive anti-HBs and anti-HBc antibodies. This occurred despite negative pre-treatment serology and led to diagnostic confusion. A negative hepatitis B viral DNA PCR confirmed the absence of an active infection. This case highlights a crucial takeaway lesson for clinicians: IVIg can interfere with viral serological assays, and this possibility should be considered to avoid misinterpretation and unnecessary interventions.