Footnotes

• Contributors AH attended the cases, analysed data and drafted the manuscript. YM analysed data, interpreted data and drafted the manuscript. KK and TB attended the cases and analysed data. SY supervised physicians, interpreted data and revised the manuscript. YM had full access to all of the data in the study and takes responsibility for the integrity of the data and accuracy of the data analysis.

• Competing interests None.

• Patient consent Informed consent was obtained from each patient after a through explanation of the procedures to be used.

• Ethics approval Ethics approval was provided by the Institutional Review Board of Chiba University Hospital.

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

• Data sharing statement Data are available from the corresponding author upon request.