**1. Introduction**

The incidence of syphilis has been increasing from the end of twentieth century—early 2000s [1, 2], warranting attention to diagnostic methods. Now we have serious problems in serologic diagnostic of different clinical forms of syphilis, including those of atypical duration, cardiovascular syphilis, neurosyphilis, congenital syphilis, latent forms, etc. Nontreponemal tests (rapid plasma regain, Venereal Disease Research Laboratory) are less reliable as there are certain situations when false-positive reactions for syphilis antibodies may appear. Variable examinations were performed and proved that it was necessary to assess the titer of antibodies, as well as confirmation of the diagnosis by treponemal tests (fluorescent treponemal antibody, treponema pallidum hemagglutination assay, enzyme immunoassay, Western blot), were obligatory. In recent decades, new methods were elaborated (e.g., BioPlex total screen, tests with β2-GPI-dependent anticardiolipin antibody, the ARCHITECT syphilis treponema pallidum chemiluminescent immunoassay, the Elecsys immunoassay (Roche Diagnostics)) [3–15] to exclude false-positive and false-negative reactions. Syphilis as the "great imitator" may be presented by a variety of clinical signs and symptoms of infection that can be easily confused with other diseases [16–18]. But in spite of miscellaneous investigations, complexities in the diagnosis of syphilis continue to challenge clinicians [19–24]. For instance, discordant maternal reverse-sequence serology is still a problem in diagnosis of congenital syphilis [25, 26]. We analyzed the papers presented in PUB MED. By the end of December 2021, the search query "False-positive reactions for syphilis" gave 743 publications. We included the papers published in English from January 2010 till the end of December 2021. We excluded the papers publicized earlier than in 2010, written in other languages than English, and those which had nothing to do with our demand "False-positive tests for syphilis". So, we analyzed 88 publications and presented our own research. We did not find any mention of false-positive tests in atopic dermatitis and present a case of false-positive reactions for syphilis in such patients.
