Review for 10.1186/s12876-021-01730-8 (2021)

Reviewer’s report
Title: 
Gastrointestinal symptoms as first remarkable signs of ANCA-associated
granulomatosis with polyangiitis: case report and review
Version: 
0 
Date: 
15 Aug 2020
Reviewer's report:
GENERAL COMMENTS
Reporting a case of GI involvement of AAV is very valuable, because it is very
rare in AAV, particularly, in GPA patients. 
MAJOR COMMENTS
BACKGROUND
1) Page 3, Line 45-48
The first paragraph does not seem closely related to the topic of this article, and
thus, it may be deleted.
2) page 3, Line 52
On the basis of 2012 revised International Chapel Hill Consensus Conference
Nomenclature of Vasculitides, "pauci-immune small vessel vasculitis" may be
changed to "ANCA-associated vasculitis" in the whole manuscript. 
3) Page 3, Line 57 and 58
Correction: (GPA, Wegener's granulomatosis) (EGPA, Churg-Strauss syndrome)
4) The authors should clarify why they selected this topic and describe the
limitations of previous reports in the background section. 
CASE PRESENTATION
5) It is better to clarify whether the first haematuria met the definition of "renal
vasculitis" on the basis of the classification of the ANCA-associated vasculitides
and polyarteritis nodosa for epidemiological studies (Ann Rheum Dis. 2007
Feb;66(2):222-7). Thus, the authors should provide more information on the
haematuria despite the normal kidney function, because renal involvement might
have preceded GI involvement of GPA.
6) were antibiotics administered to the patients prior to the initiation of
immunosuppressive drugs? Did not the authors doubt the GI infection? The
initial level of CRP (137 mg/L) was very high, which might clinically indicate
infection rather than renal limited AAV with GI symptoms.
7) Page5, Line 103-111
PR3-ANCA positivity cannot directly indicate the preference of diagnosis of
GPA rather than MPA. furthermore, the sentences should be shortened because
they seem redundant. Therefore, it may be better for the authors to briefly clarify
the clues of GPA according to the classification of the ANCA-associated
vasculitides and polyarteritis nodosa for epidemiological studies (Ann Rheum
Dis. 2007 Feb;66(2):222-7).
8) Page 5
On chest imaging tests, there were two types of lung lesions, small nodule and
GGO. In general, fixed nodules and cavitations are consider as surrogate markers
for Wegener's granulomatosis. However, GGO pattern is not one of surrogate
markers for WG. Was there any possibility of pneumonia or Tbc etc? 
9) This reviewer still does not consider a GI symptom to be the first clinical
symptom of GPA in this case, because renal manifestation seemed to precede GI
bleeding and perforation. At the first admission, there was no definite evidence
of GI involvement of GPA despite non-specific GI symptoms. 
10) Therefore, the authors should provide the histologic findings (pictures) of
resected bowel that support their argument that the bleeding and perforation of
the duodenum were owing to GI involvement of GPA. This reviewer believes
that histologic evidence is the most important and critical point of this review.
DISCUSSION and CONCLUSIONS
11) Page 6, Line 137-142
the first paragraph seems redundant and thus, it may be deleted. 
12) In addition, the description of previous reports is too vast and redundant that
it should be reduced.
13) Birmingham vasculitis activity score (BVAS) version 3 describes three cases
of abdominal manifestation of AAV, including peritonitis, bloody diarrhoea and
ischaemic abdominal pain (Ann Rheum Dis. 2009 Dec;68(12):1827-32.).
Meanwhile, BVAS for Wegener's granulomatosis describes only one case of
mesenteric ischaemia (Arthritis Rheum. 2001 Apr;44(4):912-20.). Therefore, this
reviewer asks the authors to provide evidence of bowel ischaemia with
histological findings. 
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