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Article History

Received: 14 June 2016

Accepted: 17 January 2018

First Online: 6 February 2018

Ethics approval and consent to participate

: This study was approved by the Clinical Medical Local Ethical Review Committee of the Southern Medical University. Informed written consent was provided by all men in the study.

: Consent to use the image in this publication was obtained from the patient.

: The authors declare that they have no competing interests.

: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.