Footnotes

• Contributors DV contributed to writing the manuscript, image selection, conception of the work, critical review of the article and final approval of the version to be published. TA contributed to writing the manuscript, image selection, critical review of the article and final approval of the version to be published. MN contributed to the conception of the work, critical review of the article and final approval of the version to be published. MU contributed to the conception of the work, critical review of the article and final approval of the version to be published.

• 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.

• Patient consent for publication Obtained.

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