Introduction
Oxyntic gland neoplasms (OGNs) are rare gastric lesions that mainly show differentiation to chief cells [1, 2]. In the fifth edition of the WHO classification, the OGN entity includes oxyntic gland adenoma and gastric adenocarcinoma of fundic gland type [3]. Though these subtypes are classically considered more benign, interest has been developing in a third group, gastric adenocarcinoma of fundic-gland mucosa type (GA-FG-M). GA-FG-M are distinct among OGN in that they more commonly show lymphovascular invasion on histology and are thus considered more aggressive lesions with higher malignant potential. Although interest in OGNs has been gradually increasing in the past few years, most studies had involved cases collected by tertiary referral centers, leading to a gap in the knowledge of the true disease frequency in the real-world setting. To address this issue, we previously reported the incidence of OGNs in 7488 patients in a large outpatient clinic in Japan between 2017 and 2021. However, the absolute number of OGNs was limited and the incidence of GA-FG-M was unknown [5].
Aims & Methods
The goal of this study was to more accurately characterize the disease frequency and clinicopathological characteristics of OGNs by including more than three times the number of lesions discovered since the previous report. We also aim to include an estimate for the GA-FG-M subtype. All upper gastrointestinal endoscopies performed at a high-volume outpatient clinic between December 2017 and December 2023 were retrospectively reviewed, and new cases of histologically diagnosed OGN were identified. Patient demographics, endoscopic and histopathological details are presented.
Results
During the study period, 9431 patients underwent 22322 procedures, with 85 patients having a total of 106 OGNs, resulting in a point prevalence of 0.9% (85/9431). GA-FG-M was identified in 3 patients, leading to a prevalence of 0.03% (3/9431). Fifteen patients (18%) had multiple lesions simultaneously or metachronically. Forty-six patients (54%) had a history of H. Pylori infection. Forty-nine lesions underwent endoscopic management, with 11 resected via ESD and 38 via EMR-C. The median tumor diameter was 3mm (range 2-9). Fourteen of the resected lesions had evidence of submucosal involvement. In this subset, the deepest penetration ranged from 10-950um into the submucosal layer. Median Ki67 index value was 2% (range 1-15). Thus far, there has been no evidence of recurrence on clinical follow up.
Conclusion
Though the most recent WHO classification states the prevalence of OGNs remains unknown [3], our data supports that these lesions are more common than once thought. Initial reports had suggested rates of <0.01% [6], and our previous study had found a community point prevalence of 0.36% [5]. However, in two years since that study period, the amount of lesions identified has more than tripled, leading us to a more accurate prevalence estimate of 0.9%. In addition, we clarified the prevalence of GA-FG-M to be 0.03%. It is possible this number may continue to rise in the future, as knowledge about this atypical form of gastric neoplasia is further disseminated amongst gastroenterologists and pathologists.
References
[1]Tsukamoto, Tetsuya, et al. "Gastric adenocarcinoma with chief cell differentiation." Pathology international. 2007, 57(8): 517-522.
[2] Ueyama H, Yao T, Nakashima Y, et al. Gastric adenocarcinoma of fundic gland type (chief cell predominant type): proposal for a new entity of gastric adenocarcinoma. Am J Surg Pathol. 2010, 34(5):609-619.
[3] Yao T, Vieth, M. Oxyntic gland adenoma. Digestive system tumours. In World Health Organization Classification of Tumours 5th edition (ed. WHO Classification of Tumours Editorial Board) 83–84, (International Agency for Research on Cancer, World Health Organization, 2019.
[4] Ueyama H, Yao T, Akazawa Y et al. Gastric epithelial neoplasm of fundic-gland mucosa lineage: proposal for a new classification in association with gastric adenocarcinoma of fundic-gland type. J Gastroenterol. 2021, 56(9):814-828.
[5] Asahara, Hikari, et al. "Clinicopathological Features and the Prevalence of Oxyntic Gland
Neoplasm: A Single-center Retrospective Study." Internal Medicine (2023): 0552-22.
[6] Tohda G, Osawa T, Asada Y, et al. Gastric adenocarcinoma of fundic gland type: Endoscopic and clinicopathological features. World J Gastrointest Endosc. 2016, 25(4):244-251.
Disclosure
There are no COIs to disclose in relation to this presentation.