Piecemeal resection and a positive or unclear horizontal margin is known to be associated
with risk of local recurrence. Incidence rate of local residual recurrence after incomplete
endoscopic resection is reported to be more than 20 % to 30 % [1]
[2]. Endoscopic submucosal dissection (ESD) achieves en bloc resection and R0 resection
in over 90 % of cases [3]
[4]. This high success rate contributes to a significant reduction in local residual
recurrence. In fact, incidence rate oflocal recurrence after curative resection is
reportedly extremely low [1]
[5]
[6]. On the other hand, we sometimes encounter polypoid nodules on the ESD scar even
though pathological findings show the initial ESD resulted in complete resection.
In this issue of Endoscopy International Open, Arantes et al. demonstrated the results
of a multicenter retrospective study of polypoid nodule scars (PNSs) after gastric
ESD. They analyzed a total of 2275 curative gastric ESD cases from 5 referral centers
and found that incidence of PNS was 1.2 % (3.1 % in the distal stomach), all cases
of PNS arose from the distal stomach, and approximately 20 % of PNS disappeared during
follow-up. Based on these results, they concluded that PNS is a benign alteration
of wound healing and does not require any intervention other than endoscopic surveillance.
ESD as a salvage treatment for local residual recurrence after endoscopic treatment
is a technically difficult procedure due to the severe fibrosis in the submucosal
layer from the wound healing process. In addition, there is no space to dissect, particularly
after ESD in cases in which the dissection layer is just above the muscularis propria.
Severe fibrosis results in poor visualization of the submucosal layer and increased
difficulty in identification of the dissecting plane; thus, ESD is associated with
an increased risk of perforation and incomplete resection due to injury of the specimen.
Considering the difficulty of ESC, a precise diagnosis to differentiate between PNS
and true local recurrence is important.
The precise reason PNS predominantly arises from the distal stomach is unknown. The
gastric antrum is a site of predilection for inflammatory fibroid polyps, which are
non-neoplastic cellular proliferations composed of fibroblasts, blood vessels, and
inflammatory cells [7]. This observation suggests the inflammatory reaction and wound healing process could
alternate between the antrum and the fundus/body. Differences in the properties of
gastric peristalsis, the degree of bile reflux, and the thickness of the submucosal
layer according to the location would play a role in developing PNS.
Conclusion
In conclusion, to avoid an unnecessary salvage ESD, we should consider PNS, a non-neoplastic
change, as a possibility, especially when we find a polypoid change on the ESD scar
in the distal stomach.
