Footnotes

• Contributors IA: care of patient, collection of patient data for case report, writing of original manuscript, approval of final manuscript. DW: supervision of patient care, care of patient, supervision of writing, critical review of manuscript and approval of final manuscript. LWS: rheumatology clinician advised on case and approved final manuscript. LJA: clinical pathologist supplied the images, reviewed manuscript, approved final manuscript.

• 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.

• Case reports provide a valuable learning resource for the scientific community and can indicate areas of interest for future research. They should not be used in isolation to guide treatment choices or public health policy.

• Competing interests None declared.

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