Syphilis in Dermatology: Recognition and Management

Abstract

The incidence of syphilis has been increasing in the USA since 2000. Notably, the coronavirus disease 2019 pandemic negatively impacted the public health efforts to contain the spread of sexually transmitted diseases including syphilis and congenital syphilis. Clinical manifestations of syphilis are predominantly mucocutaneous lesions, thus dermatologists are primed to recognize the myriad presentations of this disease. Primary syphilis is classically characterized by a painless transient chancre most often located in the genital area. Secondary syphilis typically manifests clinically as systemic symptoms in addition to a mucocutaneous eruption of which a variety of forms exist. Although less common in the era of effective penicillin treatment, late clinical manifestations of syphilis are described as well. In addition to recognition of syphilis on physical examination, several diagnostic tools may be used to confirm infection. Treponema pallidum spirochetes may be detected directly using histopathologic staining, darkfield microscopy, direct fluorescent antibody, and polymerase chain reaction assays. A table detailing the histopathologic features of syphilis is included in this article. Serologic testing, non-treponemal and treponemal tests, is the preferred method for screening and diagnosing syphilis infections. Two serologic testing algorithms exist to aid clinicians in diagnosing positive syphilis infection. Determining the correct stage of syphilis infection combines results of serologic tests, patient history, and physical examination findings. Using the current Centers for Disease Control and Prevention case definitions and treatment guidelines, a management algorithm is proposed here. Penicillin remains the pharmacological treatment of choice although specific clinical situations allow for alternative therapies. Syphilis is a reportable disease in every state and should be reported by stage according to individual state requirements. Screening recommendations are largely based upon risks encountered through sexual exposures. Likewise, sexual partner management includes evaluating and treating persons exposed to someone diagnosed with an infective stage of syphilis. Close clinical follow-up and repeat testing are recommended to ensure appropriate response to treatment. This guide will discuss the current epidemiology of syphilis and focus on practice aspects of diagnosis and management, including public health reporting.

Fig. 1

Primary syphilis (chancre) of the urethral meatus

Fig. 2

Secondary syphilis of the plantar surface

Fig. 3

Secondary syphilis of the palmar surfaces

Fig. 4

Condyloma lata of the anus

Fig. 5

Proposed management algorithm for the staging of treatment of syphilis using the Centers for Disease Control and Prevention (CDC) 2018 Case Definitions and the 2021 CDC Sexually Transmitted Infections Treatment Guidelines; adapted from Clement et al. 2014. a  An alternative treatment for neurosyphilis is intramuscular (IM) benzathine penicillin G (BPG) plus probenecid for 10–14 days; this should be reserved for those in which compliance can be ensured. Upon completion of neurosyphilis treatment, the treatment regimen for latent or unknown duration syphilis stages may be added for extended treatment. b When administering 2.4 million U of BPG, 1.2 million U of BPG should be intramuscularly injected per side. aPG aqueous penicillin G, CSF cerebrospinal fluid, d days, IV intravenous