Review for 10.1186/s12876-020-01565-9 (2020)

Reviewer’s report
Title: 
Endoscopic Ultrasound with Fine Needle Aspiration is useful in
pancreatic cysts smaller than 3 cm
Version: 
1 
Date: 
18 Sep 2020
Reviewer's report:
Dear Authors,
I have read again your paper. I have appreciated the effort you made to improve
your manuscript. However, I have further concerns about your manuscript that
require additional revisions. 
- To me, the background and the rationale of the study are not clear. The Authors
stated "The described risk of malignancy in cysts larger than 3 cm is about 9%
and compares to 6.5% for cysts smaller than 3 cm [8]. As such, current
guidelines may be considered too stringent [9,10,11] and the risk of missing
malignancy or high-grade dysplasia seems considerable". This sentence is
misleading, because cyst size is not the only one worrisome feature. In other
words, a cyst showing other worrisome features (including symptoms) must be
sampled even if smaller than 3cm.
- What do the Authors want to demonstrate? You stated: "The aim of our study
was to evaluate the added value of EUS-FNA for cystic fluid analysis in the
diagnosis of high-risk pancreatic cysts smaller than 3 cm". What does it mean
exactly? Please state as clear as possible the aim of your study.
- You included all the patients with small cysts who underwent FNA. However,
27% had with mural nodules and 18% symptoms, thus requiring FNA regardless
of size. To evaluate the role of EUS-FNA in small cysts, the Authors should
exclude those lesions with other worrisome features, where FNA is indicated
regardless of the cyst size, and analyze only the small cysts without other
worrisome features where FNA would not me done otherwise, and possibly,
compare with a control group of larger cysts without other worrisome feature.
This is, to me, the correct methodology to understand if FNA can have a role in
small, otherwise not-worrisome, cysts.
- As additional study aim, the Authors stated: "… and its potential to correctly
change clinical decision towards surgery". This is very difficult in retrospective
studies. Moreover, I'm not able to clearly find this result in the text. How many
times FNA changed previous decision?
- Methodology is really confusing. For example, in Figure 1 you can find "Group
A" and "Group B" which are not explained in the method section. Please try to
clarify. 
- The results are confusing and the conclusions misleading. Authors talk about
the role of mural nodules, but they had not performed contrast-enhanced EUS,
thus how can they be sure of the diagnosis of nodules?
In summary, I advise several important limitations to this study requiring deep
revision.
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Is the study design appropriate to answer the research question (including the use
of appropriate controls), and are the conclusions supported by the evidence
presented?
No
Are the methods sufficiently described to allow the study to be repeated?
Yes
Is the use of statistics and treatment of uncertainties appropriate?
Yes
Is the presentation of the work clear?
Yes
Are the images in this manuscript (including electrophoretic gels and blots) free
from apparent manipulation?
Yes