Footnotes

• Contributors MS'A is the primary author, and wrote the majority of the text. AB took the pictures and provided the captions. LB is the surgeon who operated on the patient, provided the clinical information, and reviewed the whole text. GT is the pathologist who diagnosed this entity and reviewed the whole text.

• 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.