Placental Syphilis: A Comprehensive Review of Routine Histomorphology, HIV Co-infection, Penicillin Treatment, Immunohistochemistry, and Polymerase Chain Reaction

Abstract

Introduction: Placental examination is valuable for diagnosing congenital syphilis, but the classic histological triad is not always observed. This study aimed to identify additional morphological clues, evaluate the sensitivity of IHC and qPCR, and investigate the impact of HIV co-infection and penicillin treatment on placental morphology. Materials and methods: Two hundred and fifteen placental specimens with treponemal infection were reviewed. Morphological findings, IHC, and qPCR results were analyzed. Results: Chronic villitis (94%), acute chorioamnionitis (91.6%), and villous immaturity (65.6%) were the most common abnormalities. HIV co-infection and penicillin treatment were associated with reduced frequencies of inflammatory lesions. IHC and qPCR exhibited sensitivities of 74.4 and 25.8%, respectively, confirming the diagnosis in 42 cases with negative or unknown serology. Conclusion: Villitis, chorioamnionitis, and villous immaturity were identified as the predominant placental abnormalities. HIV co-infection and penicillin treatment can impact morphology and hamper the diagnosis. IHC and q-PCR are valuable adjuncts when serology is negative.

Keywords:

• Placenta
• syphilis
• HIV
• Treponema pallidum immunohistochemistry
• Treponema pallidum PCR

Acknowledgments

The authors would like to express their gratitude to the following individuals for their contributions to the study: Ms. Ursula Paulsen, Mr. Derek Lovelot, and Ms. Pulani Mazangwe for retrieving the archived slides and FFPE tissue blocks and performing the immunohistochemical stains. Ms. Moleen Dzikiti from the Department of Biostatistics and Epidemiology at Stellenbosch University for assisting with statistical analysis. Dr. Carl Firmin, Dr. Ansunette De Wet, Dr. Renaldo Christoffels, Dr. Ruth Jooste, Dr. Alma Engelbrecht, and Mr. Winston Smeda for their assistance in retrieving clinical information for selected cases.

Author contributions

Y.A.M., P.T.S., and D.M. conceived and designed the study. Y.A.M. and P.T.S. analyzed and interpreted the data. Y.A.M. drafted the paper, and P.T.S., D.M., C.A.W., A.B., C.R.S., H.S.E., J.K., and A.J.G. critically revised it for intellectual content and provided final approval. All authors take responsibility for all aspects of the work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The corresponding author, Y.A.M., can provide the data supporting the findings of this study upon reasonable request.

Additional information

Funding

This work was supported by the National Health Laboratory Services Research Trust Development Grant [number: 94810].