The incidence of neuroendocrine tumors of the colorectum has increased during recent
years [1]. Because small lesions usually cause no symptoms and resemble colonic polyps or
other entities, the diagnosis of neuroendocrine tumor is often made by pathologic
evaluation after endoscopic resection [2].
A 50-year-old asymptomatic man underwent screening colonoscopy with polypectomy in
the rectum. Histology showed a 5-mm neuroendocrine neoplasm that contained typical
salt-and-pepper nuclei and that was positive for synaptophysin on immunohistochemical
staining. The proliferation rate of the neuroendocrine tumor was < 2 % (G1). However,
some tumor cell nests reached the deep resection margin of the specimen, so that the
pathologist classified the resection status as incomplete (R1).
Following this histopathologic diagnosis, the patient was promptly referred to our
center for further work-up. His serum chromogranin A levels were slightly elevated
(86.7 ng/mL; normal range, < 84.7). At 11 days after the polypectomy, sigmoidoscopy
showed a 10-mm resection ulcer approximately 7 cm above the dentate line. No tumor
residues were found macroscopically. Rectal endoscopic ultrasound showed neither a
residual local tumor nor pararectal lymph node metastases. Positron emission tomography
and computed tomography showed no further manifestation of tumor. The diagnosis was
neuroendocrine tumor of the rectum, < 1 cm, G1 N0 R1.
At 6 weeks after the initial polypectomy, an endoscopic full-thickness resection of
the scarred resection site was conducted ([Fig. 1]), as described previously [3]
[4]. The procedure is shown in [Video 1]. We used a novel over-the-scope device (FTRD [Full-Thickness Resection Device];
Ovesco Endoscopy, Tübingen, Germany), which consists of a 23-mm-long cap that is loaded
with a modified over-the-scope clip (OTSC) and an integrated resection snare. After
the resection area had been marked ([Fig. 2]), the rectal wall containing the scar was pulled inside the cap with a grasping
forceps (Ovesco) ([Fig. 3]). The OTSC was deployed, and an immediate full-thickness resection of the rectal
wall was performed with the integrated electrical snare (Erbe VIO, autocut mode, effect
2, 200 W; Erbe Elektromedizin, Tübingen, Germany). [Fig. 4] shows the resection site with the OTSC sealing the resection defect. There were
no complications, and the patient was able to leave the hospital on the following
day.
Fig. 1 Resection site 6 weeks after initial endoscopic mucosal resection of a 5-mm neuroendocrine
tumor found in the rectum of a patient during screening colonoscopy.
Use of a novel over-the-scope device to perform endoscopic full-thickness resection
after incomplete resection of a rectal neuroendocrine tumor.
Fig. 2 Margins of the resection site were marked with argon plasma coagulation.
Fig. 3 The area of the rectal wall containing the scar is pulled inside the cap. The picture
shows the open over-the-scope clip immediately before deployment.
Fig. 4 View of the rectum immediately after the full-thickness resection. The over-the-scope
clip seals the rectal wall defect.
Pathology showed a 2.0 × 2.5-cm full-thickness specimen of the rectal wall, with fibrosis
on the mucosal side of the specimen. No residual cells of the known neuroendocrine
tumor were found ([Fig. 5]).
Fig. 5 Hematoxylin and eosin stain of the full-thickness resection specimen. On the luminal
side (upper part), normal mucosa is seen close to the area of fibrosis due to the
initial endoscopic mucosal resection.
Small (< 1 cm) neuroendocrine tumors of the rectum with a modest proliferation rate
(G1 and G2) can be resected endoscopically [5]. If endoscopic treatment is incomplete, current guidelines allow annual surveillance
of a patient with a G1 proliferation rate [5]. However, evidence for such a cautious approach is sparse, and the only option guaranteed
to be curative is complete resection of the lesion [5].
Finally, endoscopic full-thickness resection provides a minimally invasive alternative
for achieving definitive histologic clarification in patients with microscopically
visible residual tumor cells and primarily incomplete resection.
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