OBJECTIVE

To demonstrate a case report of a rare and understudied gastric tumor.

KEY POINTS

The 76-year-old patient M. was referred to the local oncology clinic for further testing and treatment after receiving a preliminary diagnosis of a gastric polyp suspicious of a neuroendocrine tumor. During the second look gastroscopy, a submucosal lesion of the upper third of the gastric corpus up to 2 cm in diameter on the background of atrophic gastritis was detected. At the lesion’s apex, a protruding hyperemic mucosa with a hyperplastic pattern and a fibrin coating was visualized. After the examination, a preliminary diagnosis was a gastric neuroendocrine tumor. Given the submucosal localization and the absence of invasion signs, it was decided to perform a radical endoscopic treatment for extended biopsy by submucosal dissection. According to the histology, an inverted submucosal cystadenopapilloma with a focus on high-grade dysplasia and extended mostly mild dysplastic and hyperplastic changes in the epithelium of papillary lesions and pyloric phenotype epithelium.

CONCLUSION

We presented a case of diagnosis and endoscopic treatment of an inverted hyperplastic polyp of the stomach, consisting of pyloric glands with high-grade focal dysplasia.