High-grade dysplasia associated with fundic gland polyposis in a familial adenomatous polyposis patient, with special reference to APC mutation profiles

Incidence and natural history of gastric high-grade dysplasia in patients with familial adenomatous polyposis syndrome

BACKGROUND AND AIMS

Familial adenomatous polyposis (FAP) is characterized by high risks of colonic and extracolonic tumors. Recent studies have suggested a rising risk for gastric cancer (GC). We sought to define the spectrum of premalignant gastric polyps in FAP, focusing on high-grade dysplasia (HGD).

METHODS

The gastric phenotypes of 118 patients diagnosed with FAP or attenuated FAP in our Hereditary Gastrointestinal Cancer Registry were retrospectively reviewed. To analyze the clinical features associated with the diagnosis of HGD, we established an age- and sex-matched control group of FAP patients from our cohort without gastric HGD in a 4:1 ratio.

RESULTS

The spectrum and frequency of gastric polyps in individuals with FAP included fundic gland polyps (67.9%), hyperplastic polyps/foveolar hyperplasia (19.6%), tubular adenomas (15.2%), foveolar adenomas (10.7%), and pyloric gland adenomas (6.3%). Ten patients (8.9%) exhibited gastric HGD at a mean age of 55 ± 13 years, and HGD was seen in all polyp types. When compared with control subjects, HGD was associated with a high diversity of gastric polyp histology, prior low-grade dysplasia, severe gastric polyposis, and prior Whipple surgery (P = 2.0E-5, .003, .024, and .04, respectively). Two patients (1.7%) with HGD were diagnosed with GC. However, the remaining 8 patients with HGD have been under surveillance for an average of 5.8 ± 4.5 years without progression to GC.

CONCLUSIONS

Gastric HGD in FAP may be more common than previously appreciated. The natural history of HGD is variable, and most patients with HGD do not appear to progress to GC.

Novel Endoscopic Polypectomy Surveillance Technique for Fundic Gland Polyps in Familial Adenomatous Polyposis Can Improve Early Detection of Dysplasia and Gastric Cancer

INTRODUCTION

Fundic gland polyps (FGPs) are commonly found in patients with familial adenomatous polyposis (FAP) and are considered benign. Biopsies are not routinely performed, and conventional forceps may be time-consuming and/or yield nonrepresentative histology. The purpose of this study was to evaluate the role of a novel endoscopic polypectomy surveillance (EPS), a large volume cold-snare polypectomy technique of random FGPs, in the incidence of dysplasia and gastric cancer (GC) in FAP.

METHODS

This is a retrospective longitudinal cohort of patients with FAP referred to a tertiary care center for duodenal adenoma surveillance and who underwent EPS of FGPs between 2001 and 2019. Demographic, endoscopic, and clinicopathologic information was reviewed.

RESULTS

Thirty-five patients with FAP were identified at initial endoscopy by the mean age of 43.4 years (±12.8). One hundred thirteen surveillance endoscopies were performed in total using EPS. Dysplasia of FGPs was present on initial esophagogastroduodenoscopy in 7 patients (20%), and 13 additional patients (46.4%) progressed to low-grade dysplasia. Three patients (15%) who subsequently had progression to GC were found to have signet ring cell cancer within the foci of FGPs through EPS. One patient presented as metastatic GC. Progression from nondysplastic FGP to low-grade dysplasia occurred over 63 months (±46.3) with further progression to GC over 34 months (±8.5). Endoscopic risk factors for cancer were polyps >10 mm in size ( P < 0.001) and carpeting of polyps ( P < 0.001). The 5-year cumulative incidence of developing dysplasia was 35.7%.

DISCUSSION

We identified that the incidence of dysplasia and GC is higher than previously reported in patients with FAP. Our study used a novel EPS technique and was able to identify GC within the foci of FGPs. Upper endoscopic guidelines should include a more rigorous sampling method for FGPs, such as EPS, to optimize early detection of dysplasia and GC.

Prédispositions génétiques au cancer gastrique et leur association au type histologique

About 5% of gastric cancers are associated with hereditary cancer syndromes. Histology is paramount in this context, as major susceptibility genes are associated with specific subtypes. Germline pathogenic variants in CDH1 and CTNNA1 cause Hereditary Diffuse Gastric Cancer (HDGC). Major advances have been made in the past ten years regarding HDGC. Penetrance estimates for diffuse cancer are now lower than previously thought, at 30-40%. Surveillance upper gastrointestinal endoscopy is now an acceptable alternative to prophylactic total gastrectomy. Indeed, its sensitivity in detecting advanced disease is satisfactory assuming it is performed by an expert and according to a specific protocol. The risk of intestinal-type gastric cancer is increased in patients with Lynch syndrome, although it is much lower than the risk of colorectal and endometrial cancer. Intestinal-type gastric cancers are also observed in excess in patients with hereditary polyposis, the main one being APC-associated familial adenomatous polyposis. The main and most clinically relevant manifestations in patients with polyposes remain colorectal and duodenal polyps and carcinomas, well ahead of gastric cancer. Finally, recent data point towards increased gastric cancer risk in hereditary breast and ovarian cancer.

Gastric Epithelial Polyps: When to Ponder, When to Panic

This review provides an overview of different types of gastric epithelial polyps. The polyps are classified based on their cell or epithelial compartment of origin. Some of these polyps can be considered reactive or nonneoplastic, whereas others are neoplastic in origin, are sometimes associated with a hereditary polyposis/cancer syndrome, and may have malignant potential. The aim of this review is to provide a pragmatic overview for the practicing pathologist about how to correctly diagnose and deal with gastric epithelial polyps and when (not) to ponder, and when (not) to panic.

Clinical outcomes of gastric polyps and neoplasms in patients with familial adenomatous polyposis

Background and study aims Familial adenomatous polyposis (FAP) is an autosomal dominant syndrome caused by a germline mutation in the adenomatous polyposis coli (APC) gene, characterized by the presence of more than 100 adenomatous polyps in the colorectum. The upper gastrointestinal tract is an extracolonic site for malignancy in patients with FAP. The frequency of death in Japanese patients with FAP because of gastric cancer is 2.8 % and that because of colon cancer is 60.6 %. Few studies have reported upper gastrointestinal diseases in patients with FAP. In the present study, we investigated the clinical outcomes of patients with FAP diagnosed with gastric neoplasms. Patients and methods We enrolled 80 patients with FAP who underwent esophagogastroduodenoscopy from October 1997 to December 2011. We investigated patient characteristics, endoscopic findings of gastric lesions, treatment outcomes, and long-term courses. Results Fundic gland polyposis was observed in 51 patients (64 %) and gastric neoplasms in 22 patients (28 %), including 20 with non-invasive and 2 with invasive neoplasm. Of the 26 neoplasms, 11 were treated by endoscopic resection (ER) and 4 by surgical resection. Metachronous gastric neoplasms were observed in 7 patients (15 lesions) and treated by ER, except for in 1 patient. No patients died of gastric lesions during a median follow-up period of 6.5 years (range, 0 - 14). Conclusion Because gastric lesions including gastric cancers in patients with FAP did not cause any deaths, they can be considered to have favorable prognoses. Early detection of gastric neoplasms through an appropriate follow-up interval may have contributed to these good outcomes.

Two cases of adenocarcinoma occurring in sporadic fundic gland polyps observed by magnifying endoscopy with narrow band imaging

Gastric fundic gland polyps (FGPs) are common non-adenomatous gastric polyps arising from normal fundic mucosa without Helicobacter pylori (H. pylori) infection. Although systemic FGPs associated with familial adenomatous polyposis (FAP) often have dysplasia, there are few reports of dysplasia occurring in sporadic FGPs, especially when detected by magnifying endoscopy with narrow band imaging (ME-NBI). We experienced two cases of adenocarcinoma occurring in sporadic FGPs, and their ME-NBI findings were very useful for differentiating FGP with cancer from non-dysplastic FGP. A 68-year-old man and a 63-year-old woman were referred to our institution for medical checkup. H. pylori was negative in both patients. Endoscopic examination revealed a small reddish polypoid lesion on the anterior wall of the upper gastric body and several FGPs. ME-NBI showed an irregular microvascular architecture composed of closed loop- or open loop-type vascular components, plus an irregular microsurface structure composed of oval-type surface components which was different from that of FGPs. FAP was denied because of the absence of colon polyps and no familial history of FAP. Pathological diagnosis was adenocarcinoma occurring in sporadic FGP.

Point Mutations in Exon 1B of APC Reveal Gastric Adenocarcinoma and Proximal Polyposis of the Stomach as a Familial Adenomatous Polyposis Variant

Gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS) is an autosomal-dominant cancer-predisposition syndrome with a significant risk of gastric, but not colorectal, adenocarcinoma. We mapped the gene to 5q22 and found loss of the wild-type allele on 5q in fundic gland polyps from affected individuals. Whole-exome and -genome sequencing failed to find causal mutations but, through Sanger sequencing, we identified point mutations in APC promoter 1B that co-segregated with disease in all six families. The mutations reduced binding of the YY1 transcription factor and impaired activity of the APC promoter 1B in luciferase assays. Analysis of blood and saliva from carriers showed allelic imbalance of APC, suggesting that these mutations lead to decreased allele-specific expression in vivo. Similar mutations in APC promoter 1B occur in rare families with familial adenomatous polyposis (FAP). Promoter 1A is methylated in GAPPS and sporadic FGPs and in normal stomach, which suggests that 1B transcripts are more important than 1A in gastric mucosa. This might explain why all known GAPPS-affected families carry promoter 1B point mutations but only rare FAP-affected families carry similar mutations, the colonic cells usually being protected by the expression of the 1A isoform. Gastric polyposis and cancer have been previously described in some FAP-affected individuals with large deletions around promoter 1B. Our finding that GAPPS is caused by point mutations in the same promoter suggests that families with mutations affecting the promoter 1B are at risk of gastric adenocarcinoma, regardless of whether or not colorectal polyps are present.

Sporadic Fundic Gland Polyps With Low-Grade Dysplasia: A Large Case Series Evaluating Pathologic and Immunohistochemical Findings and Clinical Behavior

OBJECTIVES

Fundic gland polyps (FGPs) occur in two clinical settings, sporadic and syndromic. Epithelial dysplasia is rare in sporadic FGPs, and progression data from large series are lacking. The aim of this study was to evaluate the clinical, morphologic, and immunohistochemical features in a large series of sporadic FGPs with epithelial dysplasia.

METHODS

We studied 85 patients with FGPs with low-grade dysplasia (FGPD), including 62 patients with sporadic and 23 with syndromic FGPDs.

RESULTS

Sixty-two patients with sporadic FGPD comprised 29 men and 33 women with a median age of 56 years. The indications for endoscopy were heartburn and follow-up of Barrett esophagus, and 49 patients had a history of proton pump inhibitor use. Morphologically, sporadic and syndromic FGPDs were similar. Immunohistochemical staining for p53 was normal (weak 1+) in all polyps, Ki-67 immunohistochemistry showed staining in the mucus neck and surface epithelium, and nuclear accumulation of β-catenin was observed in 9 of 40 sporadic FGPDs. Twenty-six (42%) patients with sporadic FGPDs had follow-up esophagogastroduodenoscopies with biopsies after a mean period of 14.8 months (nine with more than one follow-up): nine (35%) had no additional polyps, 13 (50%) had nondysplastic sporadic FGPs, and four (15%) had sporadic FGPDs.

CONCLUSIONS

Sporadic FGPDs were seen primarily in middle-aged patients with gastroesophageal reflux. Follow-up data support the indolent nature of these polyps.

Familial adenomatous polyposis-associated and sporadic pyloric gland adenomas of the upper gastrointestinal tract share common genetic features

AIMS

Familial adenomatous polyposis (FAP) is a hereditary cancer predisposition syndrome caused by a germline APC mutation. A recent study showed the enrichment of pyloric gland adenomas (PGAs) of the stomach, in addition to fundic gland polyps (FGPs) and foveolar-type adenomas (FAs), in patients with FAP. In the present study, we analysed the genetic alterations in these FAP-associated gastric lesions.

METHODS AND RESULTS

Mutational statuses of GNAS and KRAS, which are frequently mutated in sporadic PGAs, as well as those of APC, were examined in PGAs, FAs and FGPs in patients with FAP using Sanger sequencing. Our analysis identified GNAS mutations in five of six PGAs (83%), but in none of the three FAs or the 40 FGPs examined. KRAS mutations were identified in four PGAs (67%), one FA (33%) and one FGP (3%). Somatic truncating APC mutations were found in all PGAs (100%), two FAs (67%) and 14 FGPs (47%). We additionally analysed sporadic PGAs of the stomach and duodenum and identified truncating APC mutations in 11 of 25 lesions (44%).

CONCLUSIONS

FAP-associated and sporadic PGAs not only show similar morphologies, but also share common genetic aberrations, including mutations of GNAS, KRAS and APC.

Mutation spectrum in the Wnt/β-catenin signaling pathway in gastric fundic gland-associated neoplasms/polyps

Frequent activation of the Wnt/β-catenin signaling pathway has recently been demonstrated in gastric adenocarcinoma/neoplasia of chief cell predominant type (GA-CCP/GN-CCP) with submucosal involvement. In this study, we examined the activation status of the Wnt/β-catenin signaling pathway in GN-CCP without submucosal involvement, which is referred to as gastric dysplasia-CCP (GD-CCP). We also examined β-catenin expression and the mutation spectrum of PPP2R1A and Wnt pathway genes in 11 cases of GD-CCP, 25 cases of gastric polyps of fundic gland type (GPs-FG), and 21 cases of GPs-FG with dysplasia (GP-FGD). β-catenin nuclear staining was observed in 3 cases of GD-CCP, none of GPs-FG, and 6 cases of GPs-FGD. Mutations in Wnt pathway genes, including PPP2R1A, were observed in 4 cases of GDs-CCP, 10 cases of GPs-FG, and 7 cases of GPs-FGD. Two of these seven GPs-FGD cases showed β-catenin nuclear staining. However, none of the 4 GD-CCP cases with mutations or the 10 GPs-FG cases with mutations showed β-catenin nuclear staining. PPP2R1A mutations were observed in 1 GD-CCP case and 1 GPs-FGD case. Although the mutation spectra of the Wnt pathway genes in GD-CCP and GP-FG differed, based on the absence of β-catenin nuclear staining despite the genetic alterations, GD-CCP is more similar to GP-FG than to GN-CCP, which shows β-catenin nuclear staining and submucosal involvement. Activation of the Wnt/β-catenin signaling by the β-catenin nuclear transition may be required during progression from GD-CCP to GN-CCP. Furthermore, this is the first report describing PPP2R1A mutations in gastric fundic gland-associated neoplasms.

Giant sporadic fundic gland polyp: Endoscopic and endosonographic features and management

Fundic gland polyps are the most common gastric polyps. They are usually small in size, sporadic and asymptomatic. We present a case of giant fundic gland polyp. Our case is particular because of the clinical presentation, the endoscopic and endosonographic documented findings, and the treatment options followed.

Familial adenomatous polyposis and the small bowel: a loco-regional review and current management strategies

Small-bowel tumours are an important cause of morbidity and death in patients with familial adenomatous polyposis. Intensive endoscopic surveillance is now standard in the long-term management of this condition. Thus, lesions occurring throughout the small bowel are increasingly noted by oesophagogastroduodenoscopy and flexible pouchoscopy. Some occur commonly de novo (in stomach, duodenum and ampulla), while others may occur following surgery (polyps of the ileostomy, ileoanal pouch, or small bowel above an anastomosis). These differ widely in incidence, natural history and management. This review provides a regional overview of these lesions, in terms of current research findings and management protocols.

Proton pump inhibitors and an emerging epidemic of gastric fundic gland polyposis

Fundic gland polyps are now commonly recognized during endoscopy. These polyps are benign, often multiple and usually detected in the gastric body and fundus. In the past, these polyps were sometimes associated with familial adenomatous polyposis. In recent years, it has become evident that increasing numbers of these polyps are being detected during endoscopic studies, particularly in patients treated with proton pump inhibitors for prolonged periods. In some, dysplastic changes in these polyps have also been reported. Recent studies have suggested that there may be no increase in risk of colon cancer with long-term proton pump inhibitor therapy. While temporarily reassuring, ongoing vigilance, particularly in those genetically predisposed to colon cancer, is still warranted.

Impact of Phospholipase A2 group IIa gene polymorphism on phenotypic features of patients with familial adenomatous polyposis

PURPOSE

Phospholipase A2 Group IIa has been suggested to be a possible disease modifier gene in familial adenomatous polyposis. This investigation was designed to elucidate possible association between phospholipase A2 Group IIa polymorphism and phenotypes of patients with familial adenomatous polyposis.

METHODS

Phospholipase A2 Group IIa was examined by polymerase chain reaction-based single strand conformation polymorphism and direct sequencing in 55 patients from 45 families with familial adenomatous polyposis. The patients were examined by gastroduodenoscopy plus biopsy with respect to fundic gland polyposis and gastroduodenal adenomas. Helicobacter pylori status was determined by rapid urease test. Contributions of genetic alteration and Helicobacter pylori infection to intestinal and extraintestinal lesions were investigated.

RESULTS

Four types of single nucleotide polymorphism were found in exon 3 of phospholipase A2 Group IIa, among which single nucleotide polymorphism in codon 32 was the most frequent. The prevalence of fundic gland polyposis was higher in patients positive for single nucleotide polymorphism of phospholipase A2 Group IIa than those negative for single nucleotide polymorphism (61 vs. 33 percent; P < 0.05). In contrast, positive rate of Helicobacter pylori infection was lower in the former than in the latter (22 vs. 52 percent; P < 0.05). The prevalence of the other phenotypes was not different significantly. Logistic regression analysis revealed a possibility toward single nucleotide polymorphism of phospholipase A2 Group IIa as an independent risk factor for fundic gland polyposis (95 percent confidence interval, 00.9-14.3; P = 0.06).

CONCLUSIONS

Phospholipase A2 Group IIa may be a modifier gene for fundic gland polyposis in patients with familial adenomatous polyposis.

Familial adenomatous polyposis predisposes to pathologic exposure of the stomach to bilirubin

BACKGROUND

The role of duodenogastric reflux in the genesis of gastric polyps in familial adenomatous polyposis (FAP), although suggested by scintigraphy scanning studies, remains unclear.

METHODS

Twenty-four hour intragastric bilirubin monitoring with the Bilitec optoelectronic device was carried out in 25 FAP patients, of whom 19 had gastric polyps (fundic gland in 13, adenomatous in 2, and both histologic types in 4) on endoscopic examination. Gastric exposure to bilirubin was expressed as the percentage of total recording time that absorbance exceeded the threshold of 0.25 and was calculated in reference to values obtained from 25 healthy volunteers. Helicobacter pylori status of the stomach was checked as well.

RESULTS

Gastric exposure to bilirubin was pathologic in 14 (56%) patients. Gastric exposure to bilirubin was of longer duration in FAP patients than in healthy volunteers (mean+/-SEM: 19%+/-4% vs 6%+/-2%) (P<.005). It increased from healthy volunteers (6%+/-2%) to FAP patients without gastric polyps (10%+/-3%), and to FAP patients with gastric polyps (22%+/-5%) (P<.004). Bilirubin exposure times were similar in FAP patients with fundic gland polyps only and in those having either adenomatous polyps only or both types of polyps (24%+/-7% vs 17%+/-4%). No patient with pathologic gastric exposure to bilirubin as well as none having gastric polyps, had H. pylori in the antrum.

CONCLUSIONS

This study shows that gastric exposure to bilirubin is of longer duration in FAP patients than in healthy volunteers, and in FAP patients with gastric polyps than in those without polyps. This study supports the existence of a direct correlation between pathologic duodenogastric reflux (DGR), the absence of H. pylori in the antrum, and the presence of gastric polyps in FAP patients.