Footnotes

• Handling editor Tristan J Barber

• Contributors HYS performed the literature search and data extraction, assessed included articles for methodological quality, wrote the first draft of the introduction, methodology and results, and revised several drafts of the manuscript. XLW performed the literature search and data extraction, reviewed the details of the systematic review, and reviewed many drafts of the manuscript. MKYC reviewed the included studies and broader literature on trichoscopic findings of syphilitic alopecia, drafted the discussion and conclusion, revised multiple drafts of the manuscript, and prepared the manuscript for submission to Sexually Transmitted Infections. DFS had significant contribution to the conception of the systematic review, mediated discrepancies during the acquisition and evaluation of data, obtained the image used for figure 2, and reviewed and revised many drafts of the manuscript. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None declared.

• Provenance and peer review Not commissioned; externally peer reviewed.

• Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.