Article History
Received: 29 January 2020
Accepted: 27 April 2020
First Online: 18 May 2020
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: This is a retrospective study. The First Affiliated Hospital of Nanjing Medical University Research Ethics Committee has confirmed that no ethical approval is required.
: Not applicable. None of the images in this manuscript contain identifying information.