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Highlighting a Potential Pitfall

Positive Treponema pallidum Immunohistochemical Stain in a Patient Without Syphilis

Pettit, Cory BS*; McMurray, Stacy MD; Randall, Milton Barry MD; Jones, Allison MD; Fisher, Kristopher MD

The American Journal of Dermatopathology: December 2019 - Volume 41 - Issue 12 - p 924–926
doi: 10.1097/DAD.0000000000001443
Brief Report

Abstract: The Treponema pallidum antibody immunohistochemical (IHC) stain has improved our ability to detect the organism histologically. We present a case of a man with genital condyloma acuminatum with a positive T. pallidum IHC stain but negative T. pallidum serologies and no syphilitic symptoms. It has been shown that the T. pallidum antibody IHC can cross-react, staining other spirochetes, including Borrelia burgdorferi and the Brachyspira family of intestinal spirochetes. Because of the proximity of our patient's lesions to the anus, and the persistently negative T. pallidum serologies, we believe nontreponemal spirochetes colonized the condyloma, giving a false-positive T. pallidum IHC. This cross-reactivity is a potential diagnostic pitfall and is important for the dermatopathologist to recognize, thereby avoiding false diagnosis of syphilis.

*The Ohio State University College of Medicine, Columbus, OH; and

Department of Dermatology, University of Tennessee Health Science Center, Memphis, TN.

Correspondence: Cory Pettit, BS, Division of Dermatology, Ohio State University Wexner Medical Center, The Ohio State University College of Medicine, 1370 Highland St. Apt E, Columbus, OH 43201 (e-mail:

The authors declare no conflicts of interest.

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