Microsatellite instability in hyperplastic and adenomatous polyps of the stomach

[Gastric adenocarcinoma arising in giant hyperplastic polyp]

Gastric hyperplastic polyps are usually solitary, their development is supposed to be associated with excessive proliferation of foveolar cells. It is essential to differentiate hyperplastic polyps from other sporadic polyps (adenomatous and fundic gland polyps) and lesions, included in familial polyposis syndromes. The frequency of adenocarcinoma in large gastric hyperplastic polyps (more than 1-2 cm in size) is about 2,1%. This article includes case report of gastric adenocarcinoma arised in large hyperplastic polyp in a 56-year-old patient. On histological examination a well-differentiated adenocarcinoma without invasion in the peduncle was identified. Immunohistochemically cells of adenocarcinoma showed elevated expression of claudin-3, CDX2, p53 and Ki67 compared to hyperplastic glands and dysplastic areas of the polyp. Also focal expression of MUC2 was revealed in adenocarcinoma. Expression of MUC5AC, CD44 and cyclin D1 was less prominent in cancer areas compared to hyperplastic and dysplastic glands. Levels of expression of claudin-1, claudin-4 and β-catenin were equal in adenocarcinoma and hyperplastic structures. Control endoscopic examination with following morphologic examination was performed three months after surgical operation. No signs of tumor growth were identified.

Malignant transformation of a gastric hyperplastic polyp in a context of Helicobacter pylori-negative autoimmune gastritis: a case report

BACKGROUND

Gastric foveolar hyperplastic polyps (GFHPs) are common findings in clinical practice. GFHPs commonly arise in a background of chronic atrophic gastritis, including autoimmune gastritis (type A gastritis), and have a potential risk of malignant transformation.

CASE PRESENTATION

In 2005, a 55-year-old Japanese woman underwent upper endoscopy at another hospital and was found to have a pedunculated polyp (10 mm in diameter) on the greater curvature of the lower gastric body. On biopsy, the polyp was diagnosed as a GFHP. Nine years later, the polyp had grown to 20 mm in diameter, and the biopsy specimen taken at this time showed tubular adenocarcinoma. On admission to our hospital, the serum Helicobacter Pylori (H. pylori) immunoglobulin G antibody and stool H. pylori antigen were both negative. Anti-gastric parietal cell antibody was positive, as was the anti-intrinsic factor antibody, and the fasting serum gastrin level was markedly increased. In 2014, en bloc resection of the pedunculated polyp was performed by endoscopic submucosal dissection. The final histological diagnosis was adenocarcinoma of the stomach with submucosal and lymphatic invasion. Subsequently, additional radical distal gastrectomy was performed. At the latest follow-up (12 months postoperatively), no recurrence was noted.

CONCLUSIONS

We here reported a rare case of malignant transformation of GFHP arising in a context of type A gastritis. To our knowledge, there are no previous reports on malignant transformation of GFHP with submucosal and lymphatic invasion arising in a background of type A gastritis in the English literature. Further, there is currently no effective treatment other than endoscopic or surgical treatment for such cases. Given the potential risk of malignant transformation due to hypergastrinemia, we consider that endoscopic treatment should be considered as a first-line therapy when a malignant growth is suspected.

Mutational analysis by next generation sequencing of gastric type dysplasia occurring in hyperplastic polyps of the stomach: Mutations in gastric hyperplastic polyps

Gastric hyperplastic polyps (GHP) are the most common type of polyps occurring in the stomach. Although GHP are broadly interpreted as benign lesions, they may progress to dysplasia and adenocarcinoma.

OBJECTIVE

In this study, we aimed to identify genomic mutations that characterize and may drive malignant transformation in GHP by using next-generation sequencing. Eight GHP (2 with dysplasia, 1 indefinite for dysplasia and 5 without dysplasia) were studied. Only large polyps (>1cm) with gastric differentiation were included in this study, while adenomatous polyps (intestinal-type) were excluded. Immunohistochemistry for MUC2, MUC5A, MUC6, CDX2, p53, and Ki67 was performed. DNA was extracted from formalin-fixed paraffin-embedded sections and sequenced for the detection of somatic mutations. Multiplex sequencing was done with the TrueSeq Amplicon Cancer Panel in the MiSeq platform. Variant annotation and visualization were performed using NextGENe (SoftGenetics) software. No pathogenic mutations were detected in GHP without dysplasia. TP53 gene mutations were the most common alteration in dysplastic GHP (2 of 2 dysplastic cases). PIK3CA mutation was identified in a GHP with pyloric-type dysplasia, whereas foveolar-type dysplasia carried TP53 mutations. In conclusion, TP53 gene mutations are a common alteration in the early dysplastic stage during malignant transformation of GHP. GHP with dysplasia may show dual differentiation. In our study, pyloric-type dysplasia was associated with a PIK3CA alteration whereas foveolar dysplasia carried TP53 mutations. The identification of carcinoma-associated mutations in large GHP provides additional evidence of their neoplastic potential and emphasizes the need for their complete resection and follow-up.

Management of gastric polyps: an endoscopy-based approach

The endoscopic finding of a gastric polyp and the histopathologic report that follows may leave clinicians with questions that have not been addressed in formal guidelines: do all polyps need to be excised, or can they just be sampled for biopsy? If so, which ones and how many should be sampled? What follow-up evaluation is needed, if any? This review relies on the existing literature and our collective experience to provide practical answers to these questions. Fundic gland polyps, now the most frequent gastric polyps in Western countries because of widespread use of proton pump inhibitors, and hyperplastic polyps, the second most common polyps notable for their association with gastritis and their low but important potential for harboring dysplastic or neoplastic foci, are discussed in greater detail. Adenomas have had their name changed to raised intraepithelial neoplasia and are decreasing in parallel with Helicobacter pylori infection; however, they do retain their importance as harbingers of gastric cancer, particularly in East Asia. Gastrointestinal stromal tumors have low incidence and no known associations, but their malignant potential is high; early diagnosis and proper management are crucial. Although rare and benign, inflammatory fibroid polyps need to recognized, particularly by pathologists, to avoid misdiagnosis. Gastric neuroendocrine tumors (carcinoids) are important because of their association with either atrophic gastritis or the multiple endocrine neoplasia syndromes; those that do not arise in these backgrounds have high malignant potential and require aggressive management. The review concludes with some practical suggestions on how to approach gastric polyps detected at endoscopy.

Adenocarcinoma occurring in a gastric hyperplastic polyp treated with endoscopic submucosal dissection

Gastric hyperplastic polyps are generally considered benign lesions, although rare cases of adenocarcinoma have been reported. Although, the underlying mechanism of carcinogenesis in gastric hyperplastic polyps is still uncertain, most malignant polyps are seen to originate from dysplastic epithelium rather than from hyperplastic epithelium. Herein, we report the case of a woman diagnosed with adenocarcinoma that originated from a hyperplastic gastric polyp that was successfully removed by endoscopic submucosal dissection. In this case, we observed adenomatous changes around the cancerous component.

Gastric polyps in patients with portal hypertension

OBJECTIVES

Gastric hyperplastic polyps are usually associated with chronic gastritis including Helicobacter pylori gastritis and postantrectomy stomachs. Here, we report on a series of 12 patients with portal hypertension secondary to liver cirrhosis, who were found to have a unique histological type of gastric polyp on endoscopy.

METHODS

Retrospective chart review of 12 patients with portal hypertension, who presented with histologically diagnosed gastric hyperplastic polyps. These polyps were reviewed and compared with hyperplastic polyps from 21 patients who did not have portal hypertension.

RESULTS

The endoscopic appearances of portal hypertension-associated polyps varied considerably, with sizes ranging up to 18 mm. They were sessile or pedunculated, singular or multiple, found in the antrum or body of the stomach, and endoscopically appeared to be typical hyperplastic polyps. Histopathological examination, however, showed mucosal hyperplasia and extensive vascular proliferation and granulation tissue formation.

CONCLUSION

The unique histological appearance of gastric hyperplastic polyps in patients with portal hypertension polyps is described. The exact pathogenetic mechanism of polyp formation is unclear although it seems possible that the underlying cause is mucosal injury that is vascular in nature rather than being secondary to surface inflammation. Although there is an emerging evidence of the neoplastic potential of usual hyperplastic polyps, the natural history of portal hypertension-associated polyps is unknown. Identification and management of portal hypertension-associated gastric polyps present a particular dilemma, as these patients often have coagulopathies and vascular ectasias. Therefore, the natural history and endoscopic features of gastric polyps arising in portal hypertensive patients warrants further exploration.

Gastroesophageal junction hyperplastic (inflammatory) polyps: a clinical and pathologic study of 46 cases

Hyperplastic (inflammatory) polyps (HPs) of the gastric corpus and antrum typically develop in association with chronic gastritis. However, little is known regarding the etiology, pathologic features, and natural history of HPs of the gastroesophageal junction (GEJ). We have noted, anecdotally, that GEJ HPs often occur in patients without gastric pathology. The aim of this study was to evaluate the clinical, pathologic, and outcome features of patients with HPs of the GEJ, and to compare the data with a control group of individuals with HPs in the gastric corpus or antrum. One hundred thirty-four consecutive polyps of the GEJ were identified by a 5-year search through the pathology files of a major tertiary-care hospital. Of these, 46 (36%) polyps from 46 patients met the pathologic criteria for HPs and formed the basis of this study. The 46 study patients, and their polyps, were evaluated for a wide variety of clinical, endoscopic, and pathologic features including outcome on follow-up endoscopy. The findings were compared with 46 HPs from 46 patients of the distal stomach (antrum or corpus) that were obtained randomly from the same 5-year period. Compared with patients with gastric antral or corpus HPs, patients with HPs of the GEJ were significantly younger in age (mean age, 55.9 y vs. 63.0 y; P=0.04). Pathologically, GEJ HPs showed a significantly higher rate of multilayered epithelium (P=0.06) and association with Barrett esophagus (BE) (P=0.0001) compared with distal gastric HPs. All BE-associated GEJ HPs were associated with either ultrashort (<1 cm) or short segment (1 to 3 cm) BE. All other pathologic variables, including intestinal metaplasia, were similar to those of distal gastric HPs. In a subanalysis, BE-associated GEJ HPs (33% of all GEJ HPs) showed a higher male to female ratio and a higher rate of intestinal metaplasia compared with all other HPs. Furthermore, none of the BE-associated GEJ HPs were associated with chronic active gastritis versus the non-BE-associated GEJ HPs, although this was not statistically significant. Only 1 HP (from the GEJ) from both the study and control groups was associated with a neoplasm (signet-ring cell carcinoma). On follow-up, 1 patient with a GEJ HP and 4 with distal gastric HPs developed recurrent HPs and none of the patients from either patient group developed dysplasia or carcinoma. In conclusion, unlike HPs of the gastric corpus or antrum, a significant proportion of HPs of the GEJ arise in association with BE and without gastric pathology. In patients with BE, the columnar-lined segment is often ultrashort, and thus, an HP may be the first clinical/endoscopic manifestation of that disorder.

[Pathology and pathobiology of the gastric carcinoma]

Recent epidemiological studies in Serbia revealed that gastric carcinoma is the third and the fifth main cause of cancer morbidity in men and women, respectively. Despite the declining incidence of gastric cancer, it remains the second most common cause of cancer-related deaths as it is worldwide. A well-defined carcinogenic inflammation-metaplasia-dysplasia-cancer sequence typically precedes the development of most gastric adenocarcinomas. Alterations such as gastric mucosal atrophy and intestinal metaplasia are merely markers of increased risk, while gastric epithelial dysplasia (GED) represent a direct precursor of cancer. DNA damage and increased mucosal proliferation secondary to H pylori infection, combined with a suitable host susceptibility phenotype (eg, genetic polymorphisms in interleukin IL-1B, IL-1RN, and tumor necrosis factor a TNF-alpha genes), are important factors in this progression pathway. However, only a small minority of patients infected with H. pylori eventually develops gastric cancer, and eradication of H pylori in these patients does not seem to eliminate the risk of cancer completely. It has been shown that atrophy may be a better indicator of risk of cancer than intestinal metaplasia, and remains to be validated in routine clinical practice according to recent proposal for new quantitative methods. It is often associated with pseudopyloric gland metaplasia in the gastric corpus mucosa, which expresses a type of trefoil peptide, the spasmolytic polypeptide (termed spasmolytic polypeptide-expressing metaplasia or SPEM) and has been shown to be linked more closely to gastric cancer than intestinal metaplasia. Better histological characterization of adenomatous (or type I), hyperplastic (foveolar or type II) and tubule-neck (mucocellular or type III) GED, two-tiered grading system (low and high grade dysplasia) as well as the introduction of Padova and Vienna international classifications of dysplasia seem to be more helpful in GED surveillance and comparative studies. A combination of histopathological features, serum markers such as pepsinogen I, and molecular tests that analyze host susceptibility polymorphisms and bacterial virulence factors, may allow development of strategies for early detection of cancer in the future. At present, pathobiology of gastric cancerogenesis is far from known, despite the progressive knowledge on predisposing environmental conditions and genetic and epigenetic abnormalities, including tumour suppressor genes, oncogenes, microsatellite instability and hypermethylation or the significance of E-cadherin mutational status association with hereditary diffuse gastric cancer syndrome. Recent evidence regarding the importance of several histopathologically derived prognostic factors, such as resection margin status and lymph node metastases and their implications have also been discussed. We aim to review these aspects, with special relevance to gastric cancer specimen reporting.

Microsatellite instability in endometrial polyps

OBJECTIVE(S)

To investigate the prevalence of microsatellite instability (MSI) in endometrial polyps and to evaluate whether there are clinical and histopathological parameters associated with this kind of instability.

STUDY DESIGN

Between September 2008 and April 2009, endometrial polyps were collected from 109 patients. MSI was evaluated using the NCI recommended markers BAT25, BAT26, D2S123, D5S346 and D17S250. Histopathological analysis was performed, and clinical information was obtained from patients' records.

RESULT(S)

MSI low was detected in 6.4% of the validated samples (7/109). Of the seven MSI that were detected, six were positive for instability at D17S250 and one at D5S346. There were no significant differences between polyps with or without MSI with regard to age, BMI, menarche, parity, miscarriage or menopause; however, MSI was more frequent in polyps with simple hyperplasia without atypia (3/20; 15%). Furthermore, patients with multiple polyps had a marginally but statistically insignificant increase in the frequency of MSI (p<0.07).

CONCLUSION(S)

This is the first prospective study of MSI in endometrial polyps using hysteroscopically obtained samples. In a population of 109 patients, MSI was infrequent in endometrial polyps. Although MSI appears to be more frequent in multiple polyps and polyps with simple hyperplasia without atypia, this was not statistically significant.

Gastric hyperplastic polyps: a review

Hyperplastic polyps represent the commonest polyp encountered in the stomach. They occur in patients of either gender and are commoner in the seventh decade of life. They are usually asymptomatic, small (less than 1 cm in diameter), solitary lesions occurring in the antrum but can present with dyspepsia, heartburn, abdominal pain, or upper gastrointestinal (GI) bleeding leading to anemia. Hyperplastic polyps almost never occur in normal gastric mucosa and are most commonly associated with chronic gastritis (Helicobacter pylori or autoimmune-induced). Pathologically, they are characterized by dilated, tortuous gastric foveoli set within an inflamed, edematous stroma. There is considerable histologic overlap especially with Ménétrier's disease and hamartomatous (juvenile or retention) polyps, and clinical input is mandatory to accomplish separation of these entities. Hyperplastic polyps arise as a by-product of repair to damaged mucosa. Dysplasia and malignancy are rarely associated with these polyps, which show an array of molecular aberrations. The importance of hyperplastic polyps for both gastroenterologist and pathologist lies in their association with other gastric mucosal pathology and mandates biopsy of adjacent mucosa and diligent search for accompanying pathology by the pathologist.

Management of gastric polyps: a pathology-based guide for gastroenterologists

1-4% of patients who undergo gastric biopsy have gastric polyps. These lesions may be true epithelial polyps, heterotopias, lymphoid tissue, or stromal lesions. Hyperplastic polyps, which arise in patients with underlying gastritis, and fundic-gland polyps, which are associated with PPI therapy, are the most common gastric polyps; however, prevalence varies widely relative to the local prevalence of Helicobacter pylori infection and use of PPI therapy. Some polyps have characteristic topography, size, and endoscopic appearance. Approximately 20% of biopsy specimens identified endoscopically as polyps have no definite pathological diagnosis. Evaluation of the phenotype of the gastric mucosa that surrounds a lesion will provide significant information crucial to the evaluation, diagnosis and management of a patient. The presence of a gastric adenoma should prompt the search for a coexistent carcinoma. The endoscopic characteristics, histopathology, pathogenesis, and management recommendations of polyps and common polypoid lesions in the stomach are discussed in this Review.

Gastric epithelial dysplasia: the Western perspective

The need for early diagnosis of gastric cancer is emphasized by the fact that gastric cancer remains the second most common cause of cancer related deaths worldwide. The aggressive surveillance and definite therapy for low and high-grade dysplasia, which can be achieved endoscopic means, remains the cornerstone of clinical management. Although the precursor status of dysplasia is not contested, its classification is controversial and fraught with marked inter-observer variations. Most cases of gastric dysplasia have an "intestinal" phenotype referred to as adenomatous dysplasia. Hyperplastic (type II dysplasia) is another less common variant. The progression of dysplasia to carcinoma is paralleled by a stepwise accumulation of multiple, but yet uncertain, genetic abnormalities. There are no immunohistochemical or molecular assays that can stratify with certainty the risk of progression to cancer. Given the low rate of transformation of low-grade dysplasia, annual endoscopic surveillance with re-biopsy is advocated. A diagnosis of indefinite for dysplasia should also prompt endoscopic surveillance. A diagnosis of high-grade dysplasia is more ominous, since it progress to cancer in most cases. However, the novel imaging and endoscopic modalities have modified management strategies with mucosal lesions amenable to endoscopic resection, while surgical resection is reserved to invasive adenocarcinoma with submucosal invasion.

Gastric preneoplastic lesions and epithelial dysplasia

The incidence of gastric cancer is declining; however, it remains the second most common cause of cancer-related deaths worldwide. This article describes gastric preneoplastic lesions and epithelial dysplasia. The possible role of Helicobacter pylori infection is emphasized.

Cyclooxygenase 2, p53, beta-catenin, and APC protein expression in gastric adenomatous polyps

Gastric adenomatous polyps are rare findings in upper gastrointestinal endoscopy; however, they are associated strongly with malignant transformation. Few series describe the oncogenic characteristics of gastric adenomas. In the present study, we immunohisto-chemically assessed the expression of cyclooxygenase (COX)-2, beta-catenin, p53, and adenomatous polyposis coli (APC) in paraffin-embedded specimens of 14 gastric adenomas. Control samples of normal gastric tissue and gastric adenocarcinoma also were analyzed. Of the adenomas, 7 demonstrated overexpression of COX-2, and all demonstrated nuclear p53 accumulation. Accumulation of beta-catenin in the nucleus and cytoplasm was detected in 38% (3/8) of specimens. Loss of APC staining was observed in 50% (4/8). Similar alterations in oncoprotein expression were seen in gastric cancers but not in normal control sections. Gastric adenomas display alterations in the expression of COX-2, beta-catenin, and APC similar to those seen in adenocarcinomas; however, accumulation of p53 was significantly more common in adenomas than in cancers.

Curative treatment of gastric cancer: towards a multidisciplinary approach?

Despite marked decreases in incidence over the last century, particularly in developed countries, gastric cancer is still the second-most common tumor worldwide. Surgery remains the gold standard for the cure of locoregional disease. However, in most countries, the diagnosis is made at an advanced stage, and the 5-year survival for surgically resectable disease stays far below 50%. The efficacy of chemotherapy and/or radiation therapy in addition to surgery has been actively studied over the last 30 years. Unfortunately, with few exceptions, most studies of adjuvant therapy in gastric cancer have given deceiving results. The purpose of this review is to address the reasons for our failure to objectivate an improvement in the cure of gastric cancer with adjuvant treatment in most trials, and to consider potential solutions. The low efficacy of chemotherapy regimens available up to now may have hampered our progress. In addition, many previous studies suffered limitations of design or methodology (e.g. low accrual, inadequate disease stage selection, inadequate surgical treatment) that may have obscured a treatment effect. Furthermore, the reduced treatment tolerance of post-gastrectomy patients, perhaps due to their poor nutritional status, results in decreased or delayed adjuvant systemic therapy, with potential adverse consequences in its efficacy. Among potential solutions, the arrival of new drugs, taxanes and topoisomerase I inhibitors in particular, which have shown encouraging results in metastatic disease, may increase the impact of chemotherapy in a multidisciplinary treatment approach. Pre-treatment with chemotherapy and/or radiation therapy prior to surgery may also be advantageous, averting the problems associated with post-surgical treatment. Such an approach has been shown to be feasible in phase II studies, and is relatively well tolerated by patients. Several carefully designed randomized phase III trials are underway to answer this question.

Epstein-Barr virus, p53 protein, and microsatellite instability in the adenoma-carcinoma sequence of the stomach

To elucidate the adenoma-carcinoma sequence in the stomach, we investigated Epstein-Barr virus (EBV) incorporation, p53 overexpression, and microsatellite instability (MSI) in gastric adenomas and carcinomas. The study involved 66 cases of gastric carcinomas within or adjacent to adenomas (adenoma-carcinoma cases), 81 cases of simple adenomas (without carcinoma), and 306 de novo carcinomas (without adenoma focus). EBV incorporation was revealed in 1 (1.5%) of the adenoma-carcinomas, in none of the adenomas, and in 17 (5.6%) of the de novo carcinomas. p53 overexpression was observed in 24.2% (16 of 66) of the adenomas in the adenoma-carcinoma cases and in 36.5% (23 of 63) of corresponding carcinomas (kappa = 0.63, P = 0.00). MSI was positive in 12.3% (8 of 65) of the adenomas in the adenoma-carcinoma cases and in 18.8% (12 of 64) of the corresponding carcinomas (kappa = 0.77, P = 0.00). In conclusion, EBV incorporation is not possibly associated with the gastric adenoma-carcinoma sequence, whereas the gastric adenoma-carcinoma sequence seems to be supported in terms of p53 overexpression or MSI. The transcriptional activation of EBV may occur relatively late (after the adenoma stage) in the gastric adenoma-carcinoma sequence.

Assessment of markers for the identification of microsatellite instability phenotype in gastric neoplasms

We tested three mononucleotide, 45 dinucleotide, and five tetranucleotide repeats in 30 gastric adenomas and 30 gastric carcinomas for microsatellite instability (MSI) in order to evaluate which microsatellites might indicate the MSI status in gastric neoplasms. Along with the increase in tested markers, the proportion of low-frequency MSI (MSI-L) tumors increased. On immunohistochemistry, MSI-L gastric neoplasms did not show any alteration in hMLH1 or hMSH2 protein expression, while most of the high-frequency MSI (MSI-H) tumors did show alterations in the above mismatch repair proteins. The above findings suggested that MSI-L tumors cannot be distinguished from microsatellite stable tumors. Two mononucleotides, BAT25 and BAT26, were sufficient for the screening of MSI. An additional three dinucleotides, D17S786, D6S105 and D19S188, were also highly sensitive and specific in identifying MSI phenotype tumors.