Comparison of characteristics between true rectal neuroendocrine tumors and rectal hyperplastic polyps among patients with endoscope-diagnosed rectal neuroendocrine tumors.

BACKGROUND

To explore the white light endoscopy and endoscopic ultrasonography (EUS) features of rectal hyperplastic polyps (rHP) misdiagnosed as rectal neuroendocrine neoplasms (rNENs). In rNENs with a diameter of 5-10 mm, the endoscopic findings are not typical and some of them are similar to rHP, so it is not uncommon to misdiagnose rNENs as rHP. However, misdiagnosis of rHP as rNENs has not been reported in the literature, which can alert clinicians to the existence of this possibility and avoid over-treatment.

METHODS

We collected 245 cases of rectal submucosal tumor (SMT) diagnosed by endoscopy in our hospital from January 2015 to December 2020 and 103 patients with suspected rNENs identified through endoscopy. A retrospective analysis was conducted of the shape, color, vascular dilatation, and boundary on the surface of the lesion under white light endoscope, and the source, boundary, and echo characteristics of EUS. We also analyzed the endoscopic features of rHP misdiagnosed as rNENs. Endoscopic diagnosis and pathological diagnosis were reviewed by a senior endoscopic expert and pathologist respectively. The counting data were tested and analyzed by χ test and Fisher exact probability method.

RESULTS

A total of 103 cases of rNENs were diagnosed by endoscope, among whom 75 cases were confirmed as rNENs (72.8%) and 8 cases as rHP (7.8%) by histopathology. There was no significant difference between rNENs and rHP in terms of gender, age, clinical manifestation, shape and color of lesions, dilatation of blood vessels on the surface, and location of lesions. Meanwhile, there were significant differences in whether the boundary of the lesion was clear under white light endoscopy, and the source, echo, and boundary of the lesion under EUS.

CONCLUSIONS

The morphology of some rHP is similar to rNENs under endoscopy. The boundary is clear under white light endoscopy and the source, echo, and boundary under EUS are helpful for the diagnosis of rNENs and rHP.