Unusual primary syphilis: Presentation of a likely case with a review of the stages of acquired syphilis, its differential diagnoses, management, and current recommendations

Int J Dermatol. 2016 Jul;55(7):714-28. doi: 10.1111/ijd.13206. Epub 2016 Jan 12.


Syphilis is an ancient disease that has re-emerged in the last decade. It is prevalent among men who have sex with men and has increased in incidence with certain ethnic groups. It usually presents as primary or secondary syphilis and can progress to tertiary syphilis if not treated. Primary syphilis will classically manifest as a single, painless ulcer with smooth, clean, and raised borders on the genitals or less often on the oral mucosa. Unusual primary syphilis cases have been reported and can be easily misdiagnosed with a resulting delay of treatment. Secondary syphilis is a systemic disease, wherein the treponemes have disseminated to various organ systems, typically presenting with characteristic mucocutaneous lesions. Tertiary syphilis has a higher rate of morbidity and mortality; as such, the aim of this article is to provide the readers with tools to recognize early syphilis and prevent its progression to late stages. In this review, we present a likely case of unusual primary syphilis mimicking herpes progenitalis as well as a compilation of all atypical cases of primary syphilis from 1973 to 2015. We will also review the differential diagnosis, management, and recommendations for each stage of syphilis.

Publication types

  • Case Reports
  • Review

MeSH terms

  • Behcet Syndrome / diagnosis*
  • Diagnosis, Differential
  • Disease Progression
  • Herpes Genitalis / diagnosis*
  • Herpes Labialis / diagnosis*
  • Humans
  • Male
  • Middle Aged
  • Penile Diseases / diagnosis*
  • Penile Diseases / drug therapy
  • Penile Diseases / pathology
  • Syphilis / diagnosis*
  • Syphilis / drug therapy*
  • Syphilis / epidemiology
  • Syphilis / pathology

Supplementary concepts

  • Syphilis, primary