Syphilitic Balanitis of Follmann: Laboratory Pitfalls

  • Filipa Tavares Almeida Department of Dermatology and Venereology, Hospital de Braga, Braga, Portugal
  • Filomena Azevedo Department of Dermatology and Venereology, Centro Hospitalar Universitário São João, Porto, Portugal
  • Carmen Lisboa Department of Dermatology and Venereology, Centro Hospitalar Universitário São João, Porto, Portugal; Division of Microbiology, Department of Pathology, Faculty of Medicine, University of Porto, Portugal; CINTESIS - Center for Health Technology and Services Research, Faculty of Medicine of the University of Porto, Portugal
Keywords: alanitis/diagnosis, Syphilis/diagnosis


We report a case of early syphilis, presenting as balanitis and papular syphilides in an HIV-infected patient, with a previous history of syphilis infection, which demonstrated a false negative VDRL testing due to a prozone phenomenon. This false negative response results from overwhelming antibody titers, which interfere with the proper formation of the antigen-antibody lattice network, necessary to visualize a positive flocculation test.


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How to Cite
Almeida, F. T., Azevedo, F., & Lisboa, C. (2020). Syphilitic Balanitis of Follmann: Laboratory Pitfalls. Journal of the Portuguese Society of Dermatology and Venereology, 78(3), 265-268.
Case Reports