Footnotes

• Contributors BJR proposed idea for manuscript. DD, PM and BJR composed the manuscript. PM was involved in the clinical care of the patient. NM did the histological analysis. All authors read and approved the final draft submitted for publication.

• 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.