Footnotes

• Handling editor Iskander Chaudhry.

• Contributors SdM conceived of the study and wrote the manuscript. MBA co-wrote the manuscript. K-SP and S-YN performed and provided the pyrosequencing data. SW provided the histopathology images and descriptions. L-MP assisted in the writing and performed a critical review of the manuscript. All authors read and approved the final manuscript.

• Competing interests None declared.

• Patient consent Obtained.

• Provenance and peer review Commissioned; internally peer reviewed.