European Journal of Case Reports in Internal Medicine
Should the traditional algorithm for syphilis screening be abandoned? Neurosyphilis presenting as limbic encephalitis: a prozone false-negative RPR missed by an RPR-only initial screen
By Hidenori Sanayama, Yuka Hayashi and Takahiko Fykuchi.
Abstract
Introduction
Neurosyphilis is a treatable mimic of viral and autoimmune limbic encephalitis. The prozone phenomenon—antibody excess preventing the antigen–antibody lattice—can render an undiluted non-treponemal test such as the rapid plasma reagin (RPR) test falsely negative, with reactivity restored on dilution.