Review for 10.1186/s12876-020-01429-2 (2020)

Reviewer’ s report
Title: Usefulness of peroral cholangioscopy in the differential diagnosis of IgG4-related sclerosing
cholangitis and extrahepatic cholangiocarcinoma: a single-center retrospective study
Version: 1Date: 12 Jun 2020
Reviewer's report:
All the comments were well answered, except comment 2 and 3.
For the answer to comment 2, the main issue of this article is the finding of IgG4-SC compared
with ECC. It is good to have table 5, but I think that the comparison between of peri-hilar anddistal ECC shown in the article has been enough.
Until now, the cholangioscopy examination is not so popular in clinical practice because of
equipment availability and high price. From the study, it is not difficult to differentiate IgG4-SCfrom ECC in distal bile duct lesion using the findings of mucosal surface and dilated vessels whenwe have general experience of image findings of other GI malignancy. However, an inexperiencedendoscopist might have a problem when we faced the proximal IgG-4 SC, which had irregularsurface and dilated vessels. I think that the key value of this study is using high image quality(compare with spyglass) to differentiate different patterns of dilated vessels between IgG4-SC andECC. Especially when we have a low yield rate of direct biopsy from the IgG4-SC lesions. Pleaseadd the description in the section of discussion.
From the comment 2 and 3:
For highlighting the significance of this study, I suggest to have a table to compare the POCS
findings beween proximal IgG4-SC and peri-hilar ECC (at least) and between distal IgG4-SC and
distal ECC.
Are the methods appropriate and well described?
If not, please specify what is required in your comments to the authors.
YesDoes the work include the necessary controls?
If not, please specify which controls are required in your comments to the authors.
YesAre the conclusions drawn adequately supported by the data shown?
If not, please explain in your comments to the authors.
Yes
Are you able to assess any statistics in the manuscript or would you recommend an
additional statistical review?If an additional statistical review is recommended, please specify what aspects require furtherassessment in your comments to the editors.
I am able to assess the statisticsQuality of written English
Please indicate the quality of language in the manuscript:
Acceptable
Declaration of competing interests
Please complete a declaration of competing interests, considering the following questions:
1. Have you in the past five years received reimbursements, fees, funding, or salary from an
organisation that may in any way gain or lose financially from the publication of thismanuscript, either now or in the future?
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose
financially from the publication of this manuscript, either now or in the future?
3. Do you hold or are you currently applying for any patents relating to the content of the
manuscript?
4. Have you received reimbursements, fees, funding, or salary from an organization that holds
or has applied for patents relating to the content of the manuscript?
5. Do you have any other financial competing interests?
6. Do you have any non-financial competing interests in relation to this paper?
If you can answer no to all of the above, write 'I declare that I have no competing interests' below.
If your reply is yes to any, please give details below.
I declare that I have no competing interestsReviewer Publication Consent. I agree for my report to be made available under an Open Access
Creative Commons CC-BY License (http://creativecommons.org/licenses/by/4.0) if this manu-script is accepted for publication. Any comments that I do not wish to be included in the publishedreport have been included as confidential comments to the editor, which will not be published.Ifyou are not happy for us to publish this report, please contact the editorial office before completingthe review.If you wish, you can include your name in your published report. Please note you mustdecide whether to include your name at the start of the process and confirm this decision wheneverprompted. If you change your decision later, we will not be able to publish your name.
I agree to the terms of the CC-BY 4.0 license; please do not publish my name with my report.
(default)
Publons Reviewer Recognition. Springer Nature can send verification of this review directly to
Publons (a subsidiary of Clarivate Analytics). If you would like to take advantage of this service,please click on the “Yes” option below. Your name, email address, title of the reviewed
manuscript, name of the journal, and date of your review submission (the “Review Data”) will
then be transmitted to Publons upon publication of the manuscript. If you have already registeredat Publons, they will notify you of the receipt of this review and update your profile as per your
settings and their policy. If you are not registered with Publons, you will receive an email from
them asking you to register in order for them to be able to recognize your review on your newprofile page. Publons may use the Review Data to generate derivative metadata for the benefit ofPublons and you as a reviewer, carefully considering the sensitivity of such information. Forexample, Publons may verify your record as a reviewer by updating your profile published on itswebservice if you have registered for such service or help editors to identify candidate reviewers.Please find the details of processing in Publons’ privacy policy https://publons.com/about/terms
No