Oxyntic gland adenoma endoscopically mimicking a gastric neuroendocrine tumor: A case report

An emerging entity of gastric adenocarcinoma: clinicopathological features and differential diagnosis of gastric adenocarcinoma of fundic-gland type in 25 retrospective cases

Gastric adenocarcinoma of fundic-gland type (GA-FG) is a rare gastric cancer with an extremely low rate of vascular and lymph node metastases. It can be cured with endoscopic submucosal dissection (ESD). However, inadequate understanding of GA-FG may lead to overtreatment, negatively impacting patient quality of life. We analyzed the clinical, endoscopic, and pathological characteristics of 25 cases of GA-FG. Immunohistochemical markers (CEA, MUC2, MUC5AC, MUC6, H + /K + ATPase, Pepsinogen-I, CgA, P53, and Ki67) were used to differentiate GA-FG from conventional gastric adenocarcinoma (CGA), neuroendocrine tumor (NET), gastric adenocarcinoma of fundic-gland mucosa type (GA-FGM), and other related conditions. The expression of β-catenin and Yes-associated protein (YAP) was also analyzed. All 25 GA-FG cases were located in the proximal stomach, with maximum diameter ranging from 4 to 20 mm. Histologically, the tumors displayed branching, mutual pulling or fusion of glandular duct structures, occasional sieve-like patterns, and mild cellular atypia. Some cases exhibited foveolar hyperplasia, with indistinct boundaries between proliferating and normal epithelium. The absence of an abrupt transition at low magnification was a critical feature to distinguish GA-FG from GA-FGM. Immunophenotypically, GA-FG resembled gastric-type adenocarcinoma with a low Ki67 index. The wild-type expression of P53 and varying Ki67 intensity patterns were helpful for diagnosing non-neoplastic hyperplasia. Abnormal β-catenin nuclear expression was found in 1 case, while 6 out of 12 showed positive YAP expression. GA-FG is a well-differentiated adenocarcinoma mimicking gastric fundic glands growth patterns. Accurate diagnosis of GA-FG is essential to accurate treatment and avoid oversurgery.

[Oxyntic gland neoplasia - case report and diagnostic dilemma]

Az oxynticus mirigy neoplasia terminológia a gyomor olyan atípusos fő- és fedősejtek által alkotott mirigyei esetében használatos, amikor nem látszik invázió, tehát a fundus mirigy adenocarcinoma diagnózisa nem állítható fel, ugyanakkor a laesio nem került kompletten eltávolításra, tehát teljes vastagsága nem vizsgálható. Az oxynticus mirigy neoplasiák etiológiája jelenleg tisztázatlan, egyes források protonpumpagátlókkal, valamint antihisztamin-használattal hozták őket összefüggésbe. Endoszkópos vizsgálat során a morfológiájuk nem specifikus, lapos és polypoid laesiók egyaránt lehetnek, és döntően a gyomor felső egyharmadára lokalizáltak. Amennyiben komplett endoszkópos nyálkahártya-reszekció kivitelezhető, további kezelés nem szükséges, tehát összességében jó prognózisú elváltozásoknak tarthatók. Közleményünkben egy 84 éves nő esetét mutatjuk be, akinél haspuffadás miatt indult kivizsgálás, és gasztroszkópia történt. A corpus területén 1 cm-es, lapos polypus volt látható, melyből többszörös biopszia történt, a képlet közel teljes eltávolításával. A szövettani vizsgálat során a nyálkahártya mélyén jól körülírt és jól differenciált, expanzív szélű elváltozás volt megfigyelhető, melyet atípusos fősejtek, elvétve pedig fedősejtek alkottak. Ezek a sejtek oxynticusmirigy-szerű struktúrákat képeztek. A pepszinogénreakció a fősejtekben szemcsés jellegű, citoplazmatikus pozitivitást mutatott. H+/K+ ATPáz reakcióval a fedősejtekben szintén szemcsés jellegű, citoplazmatikus pozitivitás látszott. MUC6-tal a laesionalis sejtekben diffúz, citoplazmatikus pozitivitás volt megfigyelhető. Invázió jeleit nem láttuk. A morfológiai, valamint az immunfenotípus alapján is az elváltozást oxynticus mirigy neoplasiának véleményeztük, ’low-grade’ dysplasiával. Az oxynticus mirigy neoplasiák mind klinikai, mint patológiai szempontból fokozott figyelmet igényelnek, ugyanis ritka entitásokról van szó, melyeknek egyelőre sem az etiológiájuk, sem a prognózisuk nem tisztázott teljes mértékben. Differenciáldiagnosztikai szempontból fundus mirigy polypus, pylorus mirigy adenoma, valamint neuroendokrin tumor jön szóba. A definitív diagnózis felállítását pepszinogén, H+/K+ ATPáz, valamint MUC6 immunhisztokémiai reakciók segíthetik. Orv Hetil. 2024; 165(27): 1053–1057.

Prevalence, clinical characteristics and treatment outcomes of oxyntic gland neoplasm: a single-center retrospective study

BACKGROUND

Oxyntic gland neoplasm (OGN) is a rare subtype of gastric cancer. The aim of this study is to evaluate the prevalence, clinicopathological features, effectiveness and safety of endoscopic treatment, as well as the prognosis of OGN.

METHODS

We retrospectively analyzed the data of patients pathologically diagnosed with OGN at our hospital from November 1, 2019 to May 1, 2023.

RESULTS

A total of 36 patients with 45 lesions were identified, resulting in a disease frequency of 0.047% (36/76,832). The mean age was 55.0 ± 7.5 years, with a male-to-female ratio of about 1:1.12. Most lesions were ≤10 mm in size (84.4%), located in the upper third of the stomach (73.3%), exhibited slight elevation (75.5%), appeared whitish (55%), had dilated blood vessels on the surface (75.5%). 16 and 21 lesions were treated by precutting endoscopic mucosal resection (EMR-P) and endoscopic submucosal dissection (ESD), respectively. No significant differences were found between EMR-P and ESD in terms of en bloc resection rate (100% vs 100%, p = 1.000), complete resection rate (100% vs 90.5%, p = 0.495), and curative resection rate (93.8% vs 90.5%, p = 1.000). No complications such as bleeding and perforation were observed. No recurrence or metastasis was observed during the follow-up period.

CONCLUSIONS

OGN is a rare tumor with unique clinical, endoscopic, and pathological characteristics. EMR-P and ESD are deemed safe and effective for treating OGNs. The relatively faster and easier EMR-P seems at least non-inferior to ESD, especially for removal of smaller OGNs. The overall prognosis is favorable.

Genetic analysis of fundic gland‑type gastric adenocarcinoma

This study aimed to analyze the molecular characteristics of gastric adenocarcinoma of the fundic-gland type (GAFG) and explore the possible mechanism of tumor development. Samples from 10 Chinese patients with GAFG were collected at the Peking University International Hospital and Liaocheng People's Hospital between January 2015 and March 2022. The nucleic acid sequence of Epstein Barr virus-encoded RNA (EBV-EBER) was detected by in situ hybridization. Genetic mutation information for GNAS, KRAS, NRAS, BRAF, PIK3CA, TP53, APC, CTNNB1, HER2, MLH1, MSH2, MSH6, and PMS2 was obtained by Next-Generation Sequencing, and the relevant literature was reviewed. A total of eight instances of missense mutations were detected, consisting of seven cases with GNAS mutations, two cases with KRAS mutations, and one case with a TP53 mutation. Additionally, two patients had simultaneous missense mutations in GNAS and KRAS. Nonsynonymous mutations in APC, CTNNB1, NRAS, BRAF, PIK3CA, HER2, MLH1, MSH2, MSH6, or PMS2 were not observed in any cases. In addition, all tumors were EBER-negative. GAFG exhibits diversity at the molecular level, and GNAS mutations are more common than KRAS mutations, TP53 mutations, and microsatellite instability. To date, no association between EBV/HER2 and GAFG has been found.

SP70 is a potential biomarker to identify gastric fundic gland neoplasms

Background

Gastric neoplasms with fundic gland differentiation include oxyntic gland adenomas (OGAs) and gastric adenocarcinomas of fundic gland type (GA-FGs). Due to their well-differentiated and similar morphology with normal fundic glands, it is usually challenging to identify these lesions in pathological diagnosis, especially in biopsy specimens. This study aims to explore and verify the potential role of a newly developed monoclonal antibody (McAb) NJ001 (SP70) in differentiating fundic neoplasms from non-neoplastic fundic gland lesions.

Methods

Twenty-three cases of histological confirmed gastric fundic gland neoplasms were obtained, including 12 cases of OGAs and 11 of GA-FGs. Fifty cases of fundic gland polyps (FGPs) were taken as the control group. Six cases of well-differentiated gastric neuroendocrine tumors (NETs) (easily misdiagnosed) were also obtained. Key clinicopathological information was collected. SP70 immunostaining was performed (with para-tumor normal fundic glands as internal control). The positive intensity and staining pattern of SP70 were analyzed and compared.

Results

In normal gastric mucosa, SP70 was strongly and diffusely stained on the cytoplasm in fundic glands, but not in the foveolar epithelium. Therefore, a zonal distribution of SP70 was observed in normal mucosa. FGPs (50/50, 100%) shared a similar expression pattern with normal fundic glands. In fundic gland neoplasms, a significant down-expression of SP70 was observed in both OGAs and GA-FGs. The positive rate of SP70 in fundic gland neoplasms (6/23, 26.1%) was significantly lower than that in FGPs (100%) (P<0.0001). There was no difference in SP70 expression between OGAs (3/12, 25.0%) and GA-FGs (3/11, 27.2%) group (P>0.05). In these 6 NET cases, SP70 was weak to moderate intensity in the majority of tumor cells (with a different expression pattern).

Conclusion

Down-expression of SP70 is a specific feature to fundic gland neoplasms including OGAs and GA-FGs. Therefore, SP70 can serve as a potential biomarker in the identification and differential diagnosis of fundic gland neoplasms.

Gastric Adenocarcinoma of the Fundic Gland Type: A Case Report

BACKGROUND Gastric adenocarcinoma of the fundic gland type (GAFG) is an extremely rare neoplasm that consists of a mixed proliferation of oxyntic and chief cells. Differential diagnosis of GAFG is difficult in the absence of infiltration. Here, we report a case of GAFG and discuss the clinicopathological features. CASE REPORT A 78-year-old man was diagnosed with gastritis and reflux esophagitis, status after esophagectomy for carcinoma of the esophagus in 2015. The patient underwent repeated gastric biopsies in 2017 and an atypical epithelium was observed, but no diagnosis was confirmed. There was no evidence of tumor extension in the submucosa. The tumor was resected via endoscopic mucosal resection, and pathological examination was performed. Microscopic findings revealed an oxyntic-type gastric mucosa with atypical dense or dilated glands with abundant pale basophilic cytoplasm and round nuclei with prominent nucleoli. The majority of the tumor cells resembled chief cells, suggesting they were derived from gastric fundic glands. However, the tumor appeared to have no submucosal infiltration or focal stromal desmoplastic reaction. Sections stained positive for MUC6 and pepsinogen-I in chief cells, and H+/K+ ATPase and PDGFRa in parietal cells, but were mostly negative for CDX2, chromogranin A, synaptophysin, and CD10. Sections stained for mib-1 expressed very low proliferative activity, with an average of 10%. Staining for TP53 overexpression was negative. CONCLUSIONS Immunostaining markers are a supportive tool for histological diagnosis of GAFG. However, if there is no infiltration, as in our case, it is difficult to consider it as a malignant tumor. Further elucidation is needed in the future, including an officially accepted diagnostic name.

Gastric epithelial neoplasm of fundic-gland mucosa lineage: proposal for a new classification in association with gastric adenocarcinoma of fundic-gland type

BACKGROUND

Gastric adenocarcinoma of fundic-gland type (GA-FG) is a rare variant of gastric neoplasia. However, the etiology, classification, and clinicopathological features of gastric epithelial neoplasm of fundic-gland mucosa lineage (GEN-FGML; generic term of GA-FG related neoplasm) are not fully elucidated. We performed a large, multicenter, retrospective study to establish a new classification and clarify the clinicopathological features of GEN-FGML.

METHODS

One hundred GEN-FGML lesions in 94 patients were collected from 35 institutions between 2008 and 2019. We designed a new histopathological classification of GEN-FGML using immunohistochemical analysis and analyzed via clinicopathological, immunohistochemical, and genetic evaluation.

RESULTS

GEN-FGML was classified into 3 major types; oxyntic gland adenoma (OGA), GA-FG, and gastric adenocarcinoma of fundic-gland mucosa type (GA-FGM). In addition, GA-FGM was classified into 3 subtypes; Type 1 (organized with exposure type), Type 2 (disorganized with exposure type), and Type 3 (disorganized with non-exposure type). OGA and GA-FG demonstrated low-grade epithelial neoplasm, and GA-FGM should be categorized as an aggressive variant of GEN-FGML that demonstrated high-grade epithelial neoplasm (Type 2 > 1, 3). The frequent presence of GNAS mutation was a characteristic genetic feature of GEN-FGML (7/34, 20.6%; OGA 1/3, 33.3%; GA-FG 3/24, 12.5%; GA-FGM 3/7, 42.9%) in mutation analysis using next-generation sequencing.

CONCLUSIONS

We have established a new histopathological classification of GEN-FGML and propose a new lineage of gastric epithelial neoplasm that harbors recurrent GNAS mutation. This classification will be useful to estimate the malignant potential of GEN-FGML and establish an appropriate standard therapeutic approach.

Morphology and genetics of pyloric gland adenomas in familial adenomatous polyposis

AIMS

Gastric pyloric gland adenomas (PGAs) are rare epithelial polyps that are found more commonly in autoimmune atrophic gastritis and familial adenomatous polyposis (FAP). Little is known about the morphology and genetics of PGAs in FAP. PGAs in FAP are studied morphologically and genetically. Findings in FAP-associated PGAs are compared to sporadic PGAs and related lesions such as oxyntic gland adenoma (OGA) to increase our understanding of these rare polyps.

METHODS AND RESULTS

Seven PGAs and 18 fundic gland polyps (FGPs) from FAP patients were collected. KRAS and GNAS mutations were determined in six PGAs and 18 FGPs. Immunohistochemistry was applied on five PGAs to provide further confirmation of the histological subtypes and genetic alterations. Morphology of all PGAs was studied and compared to literature on sporadic PGAs and related lesions. All successfully sequenced PGAs (six of six) carried GNAS mutations and half of the successfully sequenced PGAs carried a KRAS mutation (three of six). Nuclear β-catenin was seen only in one PGA with focal high-grade dysplasia. Morphologically, PGAs in FAP showed overlapping features with OGA.

CONCLUSION

Familial adenomatous polyposis-associated PGAs have a similar genetic background as sporadic PGAs, i.e. KRAS and GNAS mutation. Based on morphological findings in FAP associated PGAs, it is hypothesized that PGAs and OGAs are closely related lesions.