'Pyloric gland-type adenoma' arising in heterotopic gastric mucosa of the duodenum, with dysplastic progression of the gastric type

A case of pyloric gland adenoma with high-grade dysplasia in the duodenum arising from heterotopic gastric mucosa observed over 5 years

Pyloric gland adenoma (PGA) in the duodenum is a rare gastric phenotype duodenal neoplasm. Although heterotopic gastric mucosa in the duodenum has been recognized as a benign lesion, it is a potential precursor of PGA and gastric phenotype adenocarcinoma. Herein, we present a case follow-up of endoscopic and histological changes in the PGA in the duodenum from low-grade to high-grade dysplasia. PGA was considered to arise from the heterotopic gastric mucosa, because the heterotopic gastric mucosa was observed in the initial examination. It is difficult to distinguish heterotopic gastric mucosa from PGAs, both endoscopically and histologically. This increase in size may be useful for their differentiation. Therefore, endoscopists should not underestimate the growth of the heterotopic gastric mucosa compared to that in the previous examination.

Duodenal Gastric Metaplasia and Duodenal Neuroendocrine Neoplasms: More Than a Simple Coincidence?

Background: Duodenal gastric metaplasia (DGM) is considered a precancerous lesion. No data are available regarding its possible role as a risk factor for duodenal neuroendocrine neoplasms (dNENs). Aims: To assess the prevalence of DGM in a cohort of dNENs. Methods: Subgroup analysis of a retrospective study including dNEN patients who underwent surgical resection between 2000 and 2019 and were observed at eight Italian tertiary referral centers. Results: 109 dNEN patients were evaluated. Signs of DGM associated with the presence of dNEN were reported in 14 patients (12.8%). Among these patients, nine (64.4%) had a dNEN of the superior part of the duodenum, one (7.1%) a periampullary lesion, three (21.4%) a dNEN located in the second portion of the duodenum, with a different localization distribution compared to patients without DGM (p = 0.0332). Ten were G1, three G2, and in one patient the Ki67 was not available. In the group with DGM, six patients (35.7%) were classified at stage I, five (28.6%) at stage II, three (21.4%) at stage III, and no one at stage IV. In the group without DGM, 20 patients (31%) were at stage I, 15 (15%) at stage II, 42 (44%) at stage III, and 19 (20%) at stage IV (p = 0.0236). At the end of the study, three patients died because of disease progression. Conclusions: our findings might suggest that DGM could represent a feature associated with the occurrence of dNEN, especially for forms of the superior part of the duodenum, which should be kept in mind in the endoscopic follow up of patients with DGM. Interestingly, dNEN inside DGM showed a more favorable staging, with no patients in stage IV. The actual relationship and the clinical relevance of this possible association require further clarification.

Pyloric Gland Adenoma of the Esophagus Treated by Endoscopic Submucosal Dissection: A Case Report

A pyloric gland adenoma is a rare neoplasm that occurs most frequently in the stomach and should be removed because of its precancerous potential. Although there have been case reports of pyloric gland adenomas in extragastric areas such as the duodenum, pancreas, and bile duct, esophageal pyloric gland adenoma has never been reported in Korea. Herein, we report a case of esophageal pyloric gland adenoma that was successfully treated by endoscopic submucosal dissection.

APC mutations are common in adenomas but infrequent in adenocarcinomas of the non-ampullary duodenum

BACKGROUND

Recent studies highlighted the clinicopathological heterogeneity of non-ampullary duodenal adenomas and adenocarcinomas, but the detailed process of the malignant transformation remains unclear.

METHODS

We analyzed 144 adenomas and 54 adenocarcinomas of the non-ampullary duodenum for immunohistochemical phenotypes, genetic alterations, and mismatch repair (MMR) status to probe their histogenetic relationship.

RESULTS

The median ages of patients with adenoma and adenocarcinoma were the same (66 years). Adenomas were histologically classified as intestinal-type adenoma (n = 124), pyloric gland adenoma (PGA, n = 10), gastric-type adenoma, not otherwise specified (n = 9), and foveolar-type adenoma (n = 1). Protein-truncating APC mutations were highly frequent in adenomas (85%), with the highest prevalence in intestinal-type adenomas (89%), but rare in adenocarcinomas (9%; P = 2.1 × 10^-23). Close associations between phenotypic marker expression and genetic alterations were observed in adenomas, but not in adenocarcinomas, excluding the common association between GNAS mutations and MUC5AC expression. MMR deficiency was more frequent in adenocarcinomas (20%) than in adenomas (1%; P = 2.6 × 10^-6). One MMR-deficient adenoma and three MMR-deficient adenocarcinomas occurred in patients with Lynch syndrome. Additionally, three other patients with an MMR-deficient adenocarcinoma fulfilled the revised Bethesda criteria.

CONCLUSION

The discrepant APC mutation frequency between adenomas and adenocarcinomas suggests that APC-mutated adenomas, which constitute the large majority of non-ampullary duodenal adenomas, are less prone to malignant transformation. Non-ampullary duodenal adenocarcinomas frequently exhibit MMR deficiency and should be subject to MMR testing to determine appropriate clinical management, including the identification of patients with Lynch syndrome.

Endoscopic and Clinicopathological Features of Superficial Non-Ampullary Duodenal Tumor Based on the Mucin Phenotypes

AIMS

We aimed to clarify the endoscopic/clinicopathological features of superficial non-ampullary duodenal epithelial tumors (SNADETs) based on their mucin phenotypes.

METHODS

We analyzed 62 SNADET lesions and classified them based on mucin phenotypic expression. Endoscopic and clinicopathological findings were compared according to mucin phenotypes.

RESULTS

Eleven lesions had the gastric phenotype (GP) and 43 lesions had the intestinal phenotype (IP). All GP lesions were located in the first portion of the duodenum, while most IP lesions (72.1%) were located in the second portion (p < 0.01). Tumor size was significantly larger in the GP than in the IP group (14.4 mm vs. 10.2 mm, p < 0.05). Reddish color (72.7% in GP vs. 37.2% in IP, p < 0.05), type 0-I (72.7% vs. 11.6%, p < 0.01), lobular/granular pattern (81.8% vs. 4.7%, p < 0.01), and category 4/5 in Vienna classification (81.8% vs. 30.2%, p < 0.01) were observed significantly more often in the GP than in the IP group. Regarding findings of magnifying endoscopy with narrow-band imaging (M-NBI), white opaque substance (22.2% in GP vs. 89.7% in IP, p < 0.01) and light blue crest (0% vs. 43.6%, p < 0.05) were significantly less frequently observed in the GP group. Oval-shaped marginal epithelium (66.7% vs. 17.9%, p < 0.01), dense pattern (55.6% vs. 2.6%, p < 0.01), and dilatation of the intervening part (100% vs. 12.8%, p < 0.01) were more frequently observed in the GP group.

CONCLUSIONS

SNADETs showed distinct endoscopic/clinicopathological features according to the mucin phenotype. Tumor location, coloration, macroscopic type, and endoscopic findings including M-NBI are useful to distinguish the mucin phenotypes of SNADETs.

Duodenal neoplasms of gastric phenotype: reports of two cases and a brief review of literature

Duodenal neoplasms of gastric phenotype are uncommon epithelial neoplasms. Pyloric gland adenomas should be recognized as neoplasms with risk for transformation into invasive adenocarcinoma (). Here we report the case histories of two male patients, who presented with duodenal polypoid lesion. Endoscopic polypectomy and endoscopic submucosal dissection were carried out, respectively. Histopathologically, both polyps showed features of neoplasms of gastric phenotype. The clinical and endoscopic features, pathologic features, immunophenotype, molecular pathogenesis, clinical management and prognosis of the two cases will be discussed. We will also briefly review the latest literatures on duodenal neoplasms of gastric phenotype.

Small Bowel Epithelial Precursor Lesions: A Focus on Molecular Alterations

The wider use of gastrointestinal endoscopic procedures has led to an increased detection of small intestinal preneoplastic and neoplastic epithelial lesions, most of which are identified in the duodenum and ampullary region. Like their malignant counterparts, small intestinal glandular precursor lesions, which include adenomas and hamartomas, may arise sporadically or be associated with hereditary tumor syndromes, such as familial adenomatous polyposis, MUTYH-associated polyposis, Lynch syndrome, Peutz-Jeghers syndrome, juvenile polyposis syndrome, and Cowden syndrome. In addition, dysplastic, preinvasive lesions have been observed adjacent to small bowel adenocarcinomas complicating immune-related disorders, such as celiac or Crohn’s disease. Adenomatous lesions may exhibit an intestinal-type, gastric-type, or, very rarely, serrated differentiation, related to different molecular pathogenetic mechanisms. Finally, in the background of multiple endocrine neoplasia 1 syndrome, precursor neuroendocrine growths have been described. In this review we offer a comprehensive description on the histo-molecular features of the main histotypes of small bowel epithelial precursors lesions, including: (i) sporadic adenomas (intestinal-type and gastric-type; non-ampullary and ampullary); (ii) syndromic adenomas; (iii) small bowel dysplasia in celiac and Crohn’s disease; (iv) serrated lesions; (v) hamartomatous lesions; and (vi) neuroendocrine precursor lesions.

Large duodenal pyloric gland adenoma successfully resected by endoscopic submucosal dissection

A 71-year-old woman was given a barium meal examination as part of a workup for recurring melena and iron deficiency anemia (IDA), and it revealed a large duodenal polyp measuring 60 mm in diameter. Subsequent upper gastrointestinal endoscopy showed a large pedunculated polyp in the duodenal bulb. Magnifying endoscopy with narrow-band imaging (NBI) showed that the lesion consisted of a regular enlarged intervening part between crypts of the epithelium that resembled gastric mucosa. Although the lesion was suspected of being benign, it was resected by endoscopic submucosal dissection (ESD) to prevent the progression of the IDA. The pathology examination revealed the proliferation of mildly irregular-shaped or dilated glands lined by cuboidal cells and low columnar cells in the submucosa. The gastric glands were immunohistochemically positive for MUC6, suggesting pyloric gland differentiation. The lesion was covered by a foveolar-type epithelium, and we made a diagnosis of pyloric gland adenoma (PGA). PGAs are most common in the stomach, and they are rare in the duodenum, where endoscopic treatment is technically challenging. Here we report a case of large duodenal PGA successfully resected by ESD. Since part of PGAs has been reported to be associated with adenocarcinoma, minimally invasive treatment strategies are desirable to reduce the risk of progression to carcinoma.

Non-conventional dysplasias of the tubular gut: a review and illustration of their histomorphological spectrum

The increasing use of gastrointestinal endoscopic procedures has led to the recognition by histopathologists of non-conventional (or special-type) dysplasias of the gastrointestinal tract. These lesions can be recognised in association with prevalent underlying gastrointestinal conditions, such as Barrett oesophagus, chronic atrophic gastritis, and inflammatory bowel disease. The diagnosis of these special types can be challenging, and their biological behaviours are not fully characterised. The aim of this review is to provide a global view of non-conventional dysplastic lesions observed in the various segments of the tubular gastrointestinal tract and describe their salient features. Furthermore, as the clinical implications of these various subtypes have not been broadly tested in practice and are not represented in most management guidelines, we offer guidance on the best management practices for these lesions.

Helicobacter Infection and Gastric Adenoma

Background: We aimed to provide insight into the actual frequencies of gastric adenoma types and their association with gastritis status and associated mucosal changes with a focus on Helicobacter infection and the operative link on gastritis assessment (OLGA)/operative link on gastric intestinal metaplasia assessment (OLGIM) staging. Methods: From the archive of the Institute of Pathology in Bayreuth, we collected a consecutive series of 1058 gastric adenomas diagnosed between 1987 and 2017. Clinicopathological parameters retrieved from diagnostic reports included adenoma type and localization, associated mucosal changes in antrum and corpus (i.e., type of gastritis, the extent of intestinal metaplasia and atrophy), gender, date of birth, and date of diagnosis. Results: Intestinal-type adenoma was the most frequent adenoma (89.1%), followed by foveolar-type adenoma (4.3%), pyloric gland adenoma (3.4%), adenomas associated with hereditary tumor syndromes (2.8%), and oxyntic gland adenoma (0.4%). Adenomas were found in the background of Helicobacter pylori (H. pylori) gastritis in 23.9%, Ex-H. pylori gastritis in 36.0%, autoimmune gastritis in 24.8%, chemical reactive gastritis in 7.4%, and others in 0.1%. More than 70% of patients with gastric adenomas had low-risk stages in OLGA and OLGIM. Conclusions: We found a higher frequency of foveolar-type adenoma than anticipated from the literature. It needs to be questioned whether OLGA/OLGIM staging can be applied to all patients.

The pathology of gastric and duodenal polyps: current concepts

The liberal use of upper endoscopy has led to an increased detection of gastric and duodenal polyps, which are identified in as many as 6 and 4.6% of patient examinations, respectively. Gastroduodenal polyps are a heterogeneous group of lesions that can be neoplastic or non-neoplastic (e.g. hyperplastic or heterotopical). Most polyps present characteristic topographical features, as well as endoscopic appearance and size. Evaluation of the surrounding mucosa is essential in assessing the underlying pathology (e.g. Helicobacter pylori, autoimmune gastritis or inherited polyposis syndromes). Phylogenetically, gastric and duodenal polyps can be classified according to the epithelial compartment from which they derive. Polyps that arise from the surface epithelium can either be of foveolar or intestinal type, and they can develop from either the native mucosa or the metaplastic epithelium (gastric intestinal metaplasia or duodenal foveolar metaplasia). Other polyps develop from the deeper glandular component, such as pyloric/oxyntic gland derived subtypes. In this review we focus upon epithelial polyps, with an emphasis on the most common and clinically relevant lesions, and present recently described entities.

Clinicopathological features and risk factors for lymph node metastasis in early-stage non-ampullary duodenal adenocarcinoma

BACKGROUND

Management strategies for primary non-ampullary duodenal adenocarcinoma (NADAC) in early stage are not well established given its low incidence. This study aimed to elucidate clinicopathological features of early NADAC, including risk for lymph nodal metastasis (LNM).

METHODS

In total, 166 patients with early NADAC underwent initial treatment at our institution between 2006 and 2019, of whom 153 had intramucosal (M-) and 13 had submucosal (SM-) NADAC. These endoscopic and pathological features were retrospectively analyzed. Risk factors for LNM were evaluated in 46 early NADAC patients who underwent surgery with lymph node dissection.

RESULTS

Compared with M-NADAC, SM-NADAC was significantly more frequently located at the proximal side of the papilla, with mixed elevated and depressed macroscopic type, histologically poorly differentiated tumor and lymphovascular invasion (LVI) (85% vs. 47%, P = 0.009; 54% vs. 5%, P < 0.001; 23% vs. 0%, P < 0.001; and 46% vs. 0%, P < 0.001, respectively). The frequency of LNM was significantly higher in SM-NADAC than in M-NADAC (5/12, 42% vs. 0/34, 0%; P < 0.001). In SM-NADAC, the frequency of LNM was higher in poorly differentiated than in well to moderately differentiated tumors (3/3, 100% vs. 2/9, 22%) and higher in tumors with LVI than in those without LVI (3/5, 60% vs. 2/7, 29%). Regarding invasion depth, 2 of 4 patients with SM invasion (400 ≤ × < 500 µm) showed LNM. However, in this study, no patients developed very shallow SM invasion (0 < × < 400 µm).

CONCLUSIONS

SM-NADAC showed high LNM risk. Surgical treatment with regional lymph node dissection is recommended as a treatment strategy for SM-NADAC.

Clinicopathological features of pyloric gland adenomas of the duodenum: a multicentre study of 57 cases

AIMS

To determine the clinicopathological features of pyloric gland adenomas (PGA) that arise in the duodenum.

METHODS AND RESULTS

Fifty-seven cases of duodenal PGA were identified and analysed from 56 patients. Clinicopathological and immunohistochemical analyses were performed. PGA tend to occur in older individuals (median age = 73.5), with a slight female predominance (25 males, 31 females). PGA arise more commonly in the proximal duodenum (68.75% in D1, 25% in D2 and 6.25% in D3) and usually present as mucosal nodules (98.2%) or plaques (1.8%), with a mean size of 14.8 mm. There is associated gastric heterotopia in 22.8% of cases. PGA showing features of high-grade dysplasia were significantly larger in size than PGA, showing only low-grade dysplasia (23.1 versus 8.7 mm; P = 0.0001) and more likely to show a tubulovillous rather than a pure tubular architecture (P = 0.025). In our series, 10 of 56 patients had intramucosal or invasive carcinoma associated with the duodenal PGA (17.9%). Three of these carcinomas showed lymph node metastasis. Following definitive treatment, local recurrence occurred in only three patients.

CONCLUSIONS

Duodenal PGA tend to occur in the proximal duodenum of older individuals. Larger size and tubulovillous architecture correlates with high-grade dysplasia and associated adenocarcinoma. The low recurrence rate of these lesions would suggest that endoscopic management is appropriate, provided that the lesion can be completely resected.

Pyloric Gland Adenoma (PGA) of the Gallbladder: A Unique and Distinct Tumor from PGAs of the Stomach, Duodenum, and Pancreas

Twenty-four surgically resected, gallbladder pyloric gland adenomas (GB-PGAs) were examined and their features were compared with the reported features of stomach, duodenum, and pancreatic PGAs to better understand GB-PGAs. Clinical information on background gallbladder lesions and histologic data, including tumor grade, existence of squamoid morules, intratumoral cholesterosis, and intracytoplasmic mucins were collected. Immunohistochemical staining for MUC2, MUC5AC, MUC6, CDX2, pepsinogen I, p53, and MIB-1/nuclear β-catenin were evaluated. Targeted mutational analyses of KRAS exon2, GNAS exon 7, and CTNNB1 exon 3 were conducted. We found that 29.2% of the GB-PGAs were histologically high-grade dysplasias/carcinomas; 70.8% were low grade; and 20.8% and 33.3% contained squamoid morules and intratumoral cholesterosis, respectively. In addition, 45.8% and 54.2% of GB-PGAs were mucin-rich and mucin-poor types, respectively. Immunohistochemically, MUC6 was diffusely positive in all GB-PGAs; MUC2, MUC5AC, and CDX2 were only focally positive, and no pepsinogen-I positive cells were observed. Nuclear β-catenin accumulation was observed in all cases; however, the ratio varied among cases. Mucin-poor types were significantly associated with high histologic grade dysplasias/carcinomas and high nuclear β-catenin labeling indices. Mutational analyses identified CTNNB1 mutations in 100% of GB-PGAs (21/21), KRAS in 4.2% (1/23), and GNAS in 0% (0/22). The present study clarified the unique histologic features, phenotypic differentiation, and molecular statuses frequently associated with GB-PGAs. Altogether, our data suggest that tumorigenesis of GB-PGA is distinct from that of stomach, duodenum, and pancreatic PGAs.

Clinicopathological characteristics of non-ampullary duodenal tumors and their phenotypic classification

The tumorigenesis of non-ampullary duodenal epithelial tumors (NADETs) might be different between the oral and anal sides of Vater's papilla. We conducted an immunohistological review to elucidate the clinicopathological features according to the tumor location and phenotypic classification. A review of an institutional database identified 121 patients with 125 superficial NADETs. NADETs were histologically evaluated and classified into the intestinal or gastric type based on immunohistochemical analysis. Clinicopathological factors were compared based on the tumor location and phenotype. Logistic regression analysis was performed to identify independent predictors for gastric-type NADETs. According to location analysis, the mucin phenotype was significantly different (oral side, intestinal-type 64.8%, gastric-type 35.3%; anal side, intestinal-type 87.3%, gastric-type 12.7%; P < 0.01). Although the incidence of adenoma was significantly predominant in the intestinal type (75.3%), most gastric-type NADETs were cancerous (64.3%). Notably, most gastric-type NADETs were adenocarcinomas even when the tumor size was ≤0 mm. In multivariate analysis, tumor location on the oral side (odds ratio [OR], 4.42), villous structure (OR, 6.44), and low tumor gland density (OR, 9.49) were independent predictors of gastric-type tumors. Gastric-type NADETs significantly differ from intestinal-type NADETs in terms of tumor location, morphology, and biology.

Duodenal Epithelial Polyps: A Clinicopathologic Review

CONTEXT.—

Duodenal epithelial polyps are reported in 1.5% to 3% of individuals referred for upper endoscopy. Most duodenal epithelial polyps are asymptomatic and nonneoplastic; however, a small subset is neoplastic and may progress to adenocarcinoma. Recent advances in immunohistochemical and molecular techniques have helped further characterize these polyps, shedding light on their origin, classification, and risk of progression to adenocarcinoma.

OBJECTIVE.—

To provide a comprehensive clinicopathologic review of nonneoplastic and neoplastic duodenal epithelial polyps, with particular emphasis on recent developments in classification schemes and risk stratification based upon immunohistochemical and molecular profiles.

DATA SOURCES.—

This review is based on peer-reviewed literature and the authors' experiences.

CONCLUSIONS.—

In this review we provide an update on the clinicopathologic, immunohistochemical, and molecular features of duodenal epithelial polyps and discuss the surveillance recommendations and treatment options available. Particular attention should be placed on recognizing duodenal adenomas with intestinal, gastric, and serrated phenotype, as they have an increased risk of malignant transformation if not completely excised.

Expression of Gastric Markers Is Associated with Malignant Potential of Nonampullary Duodenal Adenocarcinoma

BACKGROUND

Sporadic nonampullary duodenal epithelial tumors (NADETs) are uncommon, and thus their clinicopathological features have not been fully assessed.

AIMS

In this study, we have analyzed a series of early sporadic NADETs, focusing on various immunohistological features.

METHODS

We conducted a multicenter retrospective analysis of 68 patients with endoscopically resected sporadic NADETs. Associations between immunohistological features and clinicopathological features were statistically analyzed.

RESULTS

The 68 patients consisted of 46 men (68%) and 22 women (32%) with a mean age of 60.7 ± 12.2 years (range 37-85 years). The 68 tumors were composed of 39 adenomas (57%) and 29 early-stage adenocarcinomas (43%). Duodenal adenocarcinomas were larger in size than adenomas and had papillary architecture in their pathological diagnosis with statistical significance. Duodenal adenocarcinomas also demonstrated a significantly higher expression of gastric markers (MUC5AC and MUC6) and a higher MIB-1 index. Duodenal adenomas were contrastively apt to express intestinal markers (MUC2, CDX1 and CDX2). Of the 68 cases analyzed, there were only 3 tumors positive for p53 staining, all of which were adenocarcinoma. When 7 submucosal invasive cancers and 21 intramucosal cancers were compared, submucosal invasion was positively associated with expression of MUC5AC. Also, submucosal invasion showed strong association with double-positivity of MUC5AC and MUC6.

CONCLUSIONS

Our results indicate that immunohistochemical evaluation is useful for predicting malignant potential of NADETs, especially focusing on the expression of gastrointestinal markers.

[Heterotopic tissue in the gastrointestinal tract]

Heterotopia of the gastrointestinal tract is a common finding. This is due to the complex embryogenesis and the relative ease to detect heterotopic tissue during endoscopy. The reason for biopsy is mostly to rule out neoplasms or to define specific causes of inflammation. Heterotopic tissue can occur in any location of the gastrointestinal tract. The most frequent are gastric heterotopia, pancreatic heterotopia, and heterotopia of Brunner's gland. On rare occasions, heterotopic tissue of salivary gland type as well as heterotopias of apocrine glands, thyroid, and prostatic tissue have been described. The most frequently involved organs are the small intestine, in particular the duodenum, the esophagus, and the stomach. Heterotopia of the large bowel occurs exclusively in the rectum. Most heterotopias do not cause symptoms and are easily diagnosed by biopsy and histology. However, depending on location, size, and the kind of underlying heterotopic tissue, they may cause significant complications, such as inflammation, ulceration and perforation, obstruction, intussusception, and severe life-threatening bleeding. Another rare but significant complication is neoplasia. Gastric heterotopias may give rise to pyloric gland adenomas within the bowel or rarely adenocarcinomas of the esophagus. Pancreatic heterotopia can be complicated by ductal type pancreatic adenocarcinomas, by acinus cell carcinomas, by intraductal papillary mucinous neoplasias, and also by endocrine tumors. The present paper summarizes our current knowledge about heterotopias in a topographic clinico-pathological manner.

Gastric pyloric gland adenoma: a multicentre clinicopathological study of 67 cases

AIMS

There is limited information regarding the clinicopathological and immunohistochemical characteristics of gastric pyloric gland adenomas (PGAs).

METHODS AND RESULTS

Sixty-seven cases of gastric PGA from 57 patients were analysed. PGAs occurred with similar frequency in men and women (47.4 and 52.6%, respectively), with a mean age of 66 years. Most presented in the gastric body/fundus (67.2%). Fifteen cases (22.4%) developed against a background of autoimmune gastritis (AIG), whereas normal mucosa was seen in 35.8%. Only 16.4% (11 cases) developed in patients with a genetic predisposition, most commonly familial adenomatous polyposis. Low-grade lesions had a mean size of 1.5 cm, while PGAs with high-grade dysplasia (HGD) or adenocarcinoma had a mean size of 3.5 cm (P < 0.001) and more commonly showed tubulovillous architecture (50.0 versus 25.6% in low-grade dysplasia; P = 0.040). Most PGAs (61.2%) co-expressed mucin (MUC)5AC and MUC6 (mixed type), which was associated significantly with HGD or adenocarcinoma (P = 0.013). AIG was also associated with HGD (P = 0.027), but genetic predisposition did not correlate with the grade of dysplasia (P = 0.793). The recurrence rate of PGA was similar for high- (11.8%) and low-grade lesions (7.4%) (P = 0.624).

CONCLUSIONS

The risk of HGD increases with the size of PGA, tubulovillous architecture and the presence of AIG as well as mixed immunophenotype. As the overall local recurrence rate is less than 10%, PGAs may be treated conservatively, but they should be excised completely if possible, particularly if they are large or show high-grade features.

Histological and molecular classification of gastrointestinal polyps

Endoscopic diagnosis and treatment for gastrointestinal polyps became widely available within the last decades. Exact terminology is important for further therapeutic steps, follow up or treatment. Gastroenterologists, Oncologists, Surgeons and Pathologists need to be aware of the most recent terminology to ensure proper risk assessment and subsequent treatment if necessary. This manuscript aims to list the variety of gastrointestinal polyps and the molecular background where appropriate.

Gastric pyloric gland adenoma

Pyloric gland adenomas are rare neoplasms of the gastrointestinal tract. Gastric pyloric gland adenomas have been shown to arise in chronically damaged mucosa. The neoplastic glands have gastric pyloric gland differentiation and have a tightly packed organization with occasional cystic dilatation. The individual cells are cuboidal to columnar, with eosinophilic to amphophilic cytoplasm and either no apical mucin cap or a poorly formed apical mucin cap. The nuclei are round to oval, with occasional prominent nucleoli. Immunohistochemically, the neoplastic cells label with markers of gastric pyloric gland differentiation, including MUC6 and MUC5AC. There is limited information regarding the natural history of pyloric gland adenomas, but clinical series have described adenocarcinomas in association with gastric pyloric gland adenomas. The ideal clinical management is adequate sampling of the lesion to investigate for high-grade dysplasia and/or invasive cancer and recommendation to clinical colleagues to investigate the background mucosa for the etiology of chronic gastritis as well as potential additional neoplastic lesions. This review will focus on gastric pyloric gland adenomas.

Activating GNAS and KRAS mutations in gastric foveolar metaplasia, gastric heterotopia, and adenocarcinoma of the duodenum

Background:

Heterotopic gastric-type epithelium, including gastric foveolar metaplasia (GFM) and gastric heterotopia (GH), is a common finding in duodenal biopsy specimens; however, there is still controversy regarding their histogenetic backgrounds.

Methods:

We analysed a total of 177 duodenal lesions, including 66 GFM lesions, 81 GH lesions, and 30 adenocarcinomas, for the presence of GNAS, KRAS, and BRAF mutations.

Results:

Activating GNAS mutations were identified in 27 GFM lesions (41%) and 23 GH lesions (28%). The KRAS mutations were found in 17 GFM lesions (26%) and 2 GH lesions (2%). A BRAF mutation was found in only one GFM lesion (2%). These mutations were absent in all 32 normal duodenal mucosa specimens that were examined, suggesting a somatic nature. Among the GFM lesions, GNAS mutations were more common in lesions without active inflammation. Analyses of adenocarcinomas identified GNAS and KRAS mutations in 5 (17%) and 11 lesions (37%), respectively. Immunohistochemically, all the GNAS-mutated adenocarcinomas diffusely expressed MUC5AC, indicating gastric epithelial differentiation.

Conclusions:

A significant proportion of GFM and GH harbours GNAS and/or KRAS mutations. The common presence of these mutations in duodenal adenoma and adenocarcinoma with a gastric epithelial phenotype implies that GFM and GH might be precursors of these tumours.

Pyloric gland adenoma in Lynch syndrome

The prevalence of gastric cancer associated with Lynch syndrome (LS) is highly variable, and the underlying histologic pathway or molecular mechanisms remain unclear. From 1995 to 2012, 15 patients had been treated for both gastric and colonic adenocarcinomas and diagnosed as LS. In all cases, pathologic review, immunohistochemical analysis for mismatch-repair proteins, and microsatellite instability (MSI) tests were performed. To confirm LS, germline mutation tests and multiplex ligation-dependent probe amplification were performed. All gastric and colonic carcinomas were MSI-high and lost expressions of MLH1/PMS2 in 11 (73%) cases and MSH2/MSH6 in 4 (27%) cases. Remarkably, in a patient with LS and germline mutation of MLH1 gene, pyloric gland adenoma (PGA) transformed to adenocarcinoma during follow-up. In 2 additional cases, PGA was found adjacent to advanced gastric cancers. All PGAs in LS patients were MSI-high and lost expression of mismatch-repair proteins (MLH1/PMS2 in 2 cases and MSH2/MSH6 in 1 case), whereas none of the 14 sporadic PGAs was MSI-high or had lost expression of mismatch-repair proteins. On the basis of these observations, although very rare, we suggest the possibility that PGA may be a precursor lesion to gastric adenocarcinoma in LS and that the mismatch-repair deficient pathway of carcinogenesis is involved early in the gastric carcinogenesis pathway.

Heterotopic gastric mucosa of the gastrointestinal tract: prevalence, histological features, and clinical characteristics

BACKGROUND

Heterotopic gastric mucosa (HGM) may be located at sites throughout the gastrointestinal (GI) tract. Clinical characteristics of HGM, role of Helicobacter pylori infection, natural history, and relationship to neoplastic transformation have not sufficiently been explored.

AIM

To retrospectively study the prevalence, histological features, and clinical characteristics of HGM among Chinese patients who underwent upper GI endoscopy.

METHODS

Endoscopic, histological, and clinical records of patients, who underwent upper GI endoscopy (n = 6802) and colonoscopy (n = 3504), respectively, between May 2011 and May 2012, were collected and retrospectively analyzed. A total of 6716 sex- and age-matched patients without HGM were enrolled as controls.

RESULTS

HGM was diagnosed in 86 cases (51 esophageal, 0.75%; 35 duodenal, 0.51%). Male:female ratio was 1.4:1 (30/21) for esophageal HGM, 1.7:1 (22/13) for duodenal HGM, and 1.1:1 (3557/3159) for controls. Two histopathological types of HGM were identified: foveolar epithelium alone and foveoloar epithelium together with gastric glands. Helicobacter pylori were present in 19.6% of cases with esophageal HGM and 20.0% of cases with duodenal HGM. Esophageal HGM was significantly associated with dysphagia and globus; duodenal HGM was not significantly associated with GI symptoms. Intestinal metaplasia was present in two and three patients in both groups, respectively, with no dysplasia or carcinoma.

CONCLUSION

HGM was present in fewer patients undergoing upper GI endoscopy, and it was more often present in men. A careful endoscopic examination is required to diagnose HGM, and it should be supported with a biopsy when indicated.

Frequent GNAS and KRAS mutations in pyloric gland adenoma of the stomach and duodenum

Gastric and duodenal adenomas exhibit a significant morphological and phenotypical diversity and are classified into intestinal-type, foveolar-type and pyloric gland adenomas. We analysed the mutations in GNAS, KRAS, BRAF and CTNNB1 and the expressions of mismatch repair (MMR) proteins in 80 gastric and 32 duodenal adenomas with histologically distinct subtypes, as well as in 71 gastric adenocarcinomas. Activating GNAS mutations were found in 22 of the 35 pyloric gland adenomas (PGAs; 63%) but in none of the foveolar-type or intestinal-type adenomas or the adenocarcinomas. Fourteen PGAs (41%), two foveolar-type adenomas (9%), five intestinal-type adenomas (9%) and one adenocarcinoma (1%) had KRAS mutations. BRAF mutations were absent in all the adenomas and adenocarcinomas that were examined. CTNNB1 mutations were only found in two intestinal-type adenomas (4%). Notably, 13 of the 14 KRAS-mutated gastric and duodenal PGAs had concurrent GNAS mutations. The loss of the MMR proteins, which is indicative of microsatellite instability, was observed in one PGA (3%), 12 foveolar-type adenomas (52%), one intestinal-type adenoma (2%) and five adenocarcinomas (7%). These observations indicate that each histological subtype of gastric and duodenal adenomas has a distinct genetic background. In particular, the present study identified the frequent presence of activating GNAS mutations, which are often associated with KRAS mutations, as a characteristic genetic feature of PGAs of the stomach and duodenum.

Pyloric gland adenoma of the cystic duct with malignant transformation: report of a case with a review of the literature

Background

Pyloric gland adenoma consists of closely packed pyloric-type glands lined by mucus-secreting cells. To date, approximately 230 cases have been reported, mostly of gastric localization with a tumour size up to 3.5 cm and a mean age of occurrence around 70 years. Adenocarcinoma develops in about 40% of cases and may be difficult to detect due to relatively mild nuclear atypia.

Case presentation

We present the first case of a pyloric gland adenoma of the cystic duct in a 62-year-old male patient and demonstrate the clinicopathologic characteristics, including radiographic, molecular, and cytogenetic findings. The 2 cm-tumour developed in the cystic duct and protruded into the hepatic and common bile duct. On microscopic examination, it displayed closely packed pyloric-type glands, and focal architectural distortion with mild nuclear atypia. Immunohistochemically, it expressed MUC1, MUC5AC, MUC6 and p53, but not MUC2 and CD10. The Ki67-proliferation index was 25%. Furthermore, high-grade intraepithelial neoplasia was observed in the surrounding bile duct. We detected chromosomal gains at 7p, 7q11q21, 15q, 16p, 20, losses at 6p23pter, 6q, 18, and amplifications at 1q and 6p21p22 in the pyloric gland adenoma by comparative genomic hybridization. A KRAS codon 12 mutation (c.35G>T; p.G12V) was detected in the pyloric gland adenoma and in the adjacent dysplasia by sequencing analysis. The diagnosis of pyloric gland adenoma was established with transition into well-differentiated adenocarcinoma and high-grade biliary intraepithelial neoplasia.

Conclusion

Pyloric gland adenoma evolving in the cystic duct is a rare differential diagnosis of obstructive bile duct tumours. Other premalignant bile duct lesions may be associated. Due to the risk of developing adenocarcinoma, surgical resection should be performed.

Diagnostic value of endoscopic and endoscopic ultrasound characteristics of duodenal submucosal tumour-like heterotopic gastric mucosa

OBJECTIVE

Recent studies have reported that duodenal heterotopic gastric mucosa (HGM) has been observed in 8.9% of patients who undergo esophagogastroduodenoscopy. However, there are few reports concerning the endoscopic and endoscopic ultrasound characteristics of submucosal tumour-like HGM in the duodenum.

METHODS

Endoscopic, endoscopic ultrasound (EUS) and histological findings were analyzed in six patients with submucosal tumour-like HGM, which were confirmed by pathological examination of biopsy or endoscopic polypectomy specimens.

RESULTS

Endoscopically, the lesions appeared as a solitary, sessile submucosal tumour-like mass with a depression at the top. In four of six patients, small granular structures were found in the depressed area of the mass. On EUS, all masses demonstrated a heterogeneous pattern, among which four patients presented anechoic areas while two patients showed no anechoic areas. All lesions were localized within the mucosa and submucosa on EUS. Histologically, they consisted of gastric glands and some dilated glands, and were covered with normal duodenal epithelium. In four of six lesions, the tumours were composed of gastric-type foveolar epithelium showing papillary growth, fundic glands and pyloric glands, while the others consisted of gastric-type foveolar epithelium and pyloric glands.

CONCLUSION

A heterogeneous pattern on EUS and small granular structures on esophagogastroduodenoscopy represent valuable diagnostic features of submucosal tumour-like HGM.

Duodenal adenocarcinoma arising from a pyloric gland adenoma with a brief review of the literature

Pyloric gland-type adenoma of the duodenum with documented malignant progression is rare. A case is presented of an 87-year-old man with bloating and nausea, who on investigation was found to have a polyp on the anteroinferior wall of the duodenal cap. Histologic examination of the polyp showed features of a pyloric gland adenoma (PGA) demonstrating the full spectrum of progression from low- to high-grade dysplasia and finally invasive adenocarcinoma. The carcinoma showed gastric-type differentiation highlighted by its mucin immunohistochemistry profile and was of advanced stage with lymph node metastasis. The literature on PGAs and the little documentations on progression to carcinoma in duodenal PGAs are reviewed.

Immunohistochemical analysis of pyloric gland adenomas using a series of Mucin 2, Mucin 5AC, Mucin 6, CD10, Ki67 and p53

A pyloric gland adenoma (PGA) of the stomach was first described in a book chapter in 1976 by Kurt Elster and has been rarely reported in the literature. We expanded the current immunohistochemical data of these adenomas in a detailed series to further analyse the immunhistochemical status of PGA. From 60 patients with PGA with and without adenocarcinomas of the gastrointestinal tract, an immunhistochemical panel of Mucin 2, Mucin 5AC, Mucin 6, CD10, Ki67 and p53 was used to define the expression of these markers. All PGA were positive for Mucin 6 (deep mucoid glands), which they express over the whole lesion up to the surface. Mucin 5AC expression varies from case to case. A transition from gastric to intestinal differentiation can be observed focally as depicted by Mucin 2 and CD10 in 65% of the cases. The gastric corpus mucosa of elderly patients with either Helicobacter pylori gastritis or autoimmune gastritis is highly affected. Almost 47% of all PGA already underwent malignant transformation into adenocarcinoma. Significant immunohistochemical differences could be detected between PGA with and without adenocarcinoma regarding ki67 and p53. The diagnosis of PGA can be confirmed immunohistochemically by staining against apomucin 6 and apomucin 5AC. Focal intestinal differentiation supports the hypothesis that gastric adenocarcinomas can initially develop from carcinomas of the gastric type and transform into intestinal type later on. The high frequency of malignant transformation of PGA underlines its high potential for invasive malignancy.

[Tubular adenoma of the stomach with special reference to the Japanese criteria and pyloric gland adenoma]

The term gastric adenoma usually refers to a flat adenoma of the intestinal type. Adenomas of the gastric type, so-called pyloric gland adenomas (PGA), which was first characterized by German and Japanese pathologists in 1990, have been regarded as exceptional until recently. In 2003, we first reported systematic clinical pathological analyses of PGA, demonstrating its unstable and precancerous nature. American gastrointestinal pathologists have finally recognized this disease entity in 2009. In this article we introduce the Japanese criteria of the gastric adenoma and review and discuss the clinical pathological and molecular aspects of PGAs.

Pyloric gland adenoma: an entity distinct from gastric foveolar type adenoma

Pyloric gland adenoma (PGA) is a rare neoplasm demonstrating gastric epithelial differentiation. In this series, we studied 41 PGAs from 36 patients. We compared them to 28 gastric foveolar type gastric adenomas (GTAs) from 25 patients. PGAs occurred in an older population with a mean age of 73 compared with 48 in GTAs (P<0.001). There was a significant female predominance, particularly for gastric PGAs. Morphologically, PGAs were characterized by closely packed pyloric gland-type tubules with a monolayer of cuboidal to low columnar epithelial cells containing round nuclei and pale to eosinophilic cytoplasm with a ground glass appearance. The cells lacked an apical mucin cap, a feature distinct from GTAs. An immunohistochemical panel of mucin core peptides (MUCs) and CDX2 was performed on a subset of the lesions. All PGAs expressed MUC6 with coexpression of MUC5AC, whereas GTAs expressed predominantly MUC5AC without MUC6. Both lesions lacked CDX2 and MUC2 except in areas of intestinal metaplasia (IM) found in some PGAs. Histologic features consistent with conventional dysplasia were found in 26 (63.4%) PGAs. Using a 2-tier grading system, 5 (12.2%) cases demonstrated low-grade dysplasia whereas 21 (51.2%) cases showed high-grade dysplasia including 5 (12.2%) cases with an associated intramucosal or more deeply invasive adenocarcinoma. This was significantly different from GTAs; all cases showed only low-grade dysplasia (P<0.001). In addition, 60% of gastric PGAs were associated with IM in the surrounding mucosa and 40% of lesions arose in a background of autoimmune gastritis, whereas these 2 conditions were only associated with 1 case (3%) of GTA. In summary, PGA is a distinct entity. Despite its bland histologic appearance, it is much more likely to be accompanied by background IM and autoimmune gastritis and can evolve into invasive adenocarcinoma displaying pyloric gland differentiation.

DNA copy number profiles of gastric cancer precursor lesions

Background

Chromosomal instability (CIN) is the most prevalent type of genomic instability in gastric tumours, but its role in malignant transformation of the gastric mucosa is still obscure. In the present study, we set out to study whether two morphologically distinct categories of gastric cancer precursor lesions, i.e. intestinal-type and pyloric gland adenomas, would carry different patterns of DNA copy number changes, possibly reflecting distinct genetic pathways of gastric carcinogenesis in these two adenoma types.

Results

Using a 5K BAC array CGH platform, we showed that the most common aberrations shared by the 11 intestinal-type and 10 pyloric gland adenomas were gains of chromosomes 9 (29%), 11q (29%) and 20 (33%), and losses of chromosomes 13q (48%), 6(48%), 5(43%) and 10 (33%). The most frequent aberrations in intestinal-type gastric adenoma were gains on 11q, 9q and 8, and losses on chromosomes 5q, 6, 10 and 13, whereas in pyloric gland gastric adenomas these were gains on chromosome 20 and losses on 5q and 6. However, no significant differences were observed between the two adenoma types.

Conclusion

The results suggest that gains on chromosomes 8, 9q, 11q and 20, and losses on chromosomes 5q, 6, 10 and 13, likely represent early events in gastric carcinogenesis. The phenotypical entities, intestinal-type and pyloric gland adenomas, however, do not differ significantly (P = 0.8) at the level of DNA copy number changes.

Gastric-type well-differentiated adenocarcinoma and pyloric gland adenoma of the stomach

Since 1985, when gastric-type well-differentiated adenocarcinomas were demonstrated in hyperplastic polyps of the stomach, we have studied phenotypic expression in gastrointestinal epithelial lesions. The recent discovery of MUC genes coding core proteins of mucin has improved research on the phenotypic expression of gastrointestinal neoplasms. The disease entity of gastric-type well-differentiated adenocarcinoma has recently been accepted, especially in Japan and Europe. This entity has often become a clinicopathological subject of discussion, because its biological behavior is possibly highly malignant, in spite of the difficulty in making endoscopic and histopathological diagnoses. Even under these circumstances, the term "gastric adenoma" usually means flat adenoma of the intestinal type. Gastric-type adenomas have been regarded as exceptional until recently. Although gastric-type adenomas could theoretically be classified into foveolar type and pyloric-gland type, foveolar-type adenoma is, in practice, difficult to distinguish from gastric-foveolar-type adenocarcinoma. In 2003, we first reported systematic clinicopathological analyses of pyloric gland adenoma, demonstrating its unstable and precancerous nature. In this article, we review and discuss the clinicopathological and molecular pathological aspects of gastric-type well-differentiated adenocarcinomas and pyloric gland adenomas, mainly based on our published and unpublished data.

Pyloric gland adenoma arising in Barrett's esophagus with mucin immunohistochemical and molecular cytogenetic evaluation

Pyloric gland adenoma is a recently described and very rare entity. The occurrence of adenoma is very unusual in Barrett's epithelium of the esophagus. We report a case of esophageal polyp showing the features of pyloric gland adenoma, which was surrounded by so-called specialized columnar epithelium. Immunohistochemically, most tumor glands were strongly positive for MUC6, except in the superficial layer. MUC5AC was positive in almost all tumor cells, but MUC2 and CD10 were negative in the tumor. MIB-1-positive proliferating cells were distributed throughout the tumor. Microdissection and comparative genomic hybridization analyses revealed losses on 2p24-25.2, 2q14.1-ter, 5q31.3-32, 6q23-24, 8q23-24.2, 11q22.3-24 and 18q21.1-22. This is the first case of pyloric gland adenoma found to arise in Barrett's epithelium of the esophagus, showing its unstable and precancerous nature.

Adenoma with gastric differentiation (so-called pyloric gland adenoma) in a heterotopic gastric corpus mucosa in the rectum

In a 46-year-old man, a pedunculated rectal polyp measuring 3.0x3.0x2.0 cm was diagnosed histologically as a pyloric gland-type adenoma arising in heterotopic gastric corpus mucosa. The luminal site was covered by glands of the gastric foveolar type, displaying focal marked proliferation interpreted as low-grade intraepithelial neoplasia. A bidirectional gastric differentiation was found: most lower glandular structures showed positivity for the deep gastric mucin core protein Muc 6 and superficial positivity for gastric foveolar epithelium mucin core protein Muc 5AC. Pyloric gland adenoma has so far been described in one larger series only and a few case reports of the stomach, gallbladder, pancreatic duct and within heterotopic gastric corpus mucosa of the duodenal bulb. The present case report is the first case of a pyloric gland-type adenoma within a gastric corpus heterotopia of the rectal mucosa.

Pyloric gland adenoma: a clinico-pathological analysis of 90 cases

BACKGROUND

Pyloric gland adenoma is a rarely described neoplasia of the gastric mucosa. Recent publications have shown that similar lesions are also found in the gallbladder, the main pancreatic duct, the duodenum and the cervix of the uterus. Apart from case reports, few clinical data are available on these patients. We therefore conducted a search of the archived material collected between 1990 and 2000 for more clinical data on patients with this rare lesion.

PATIENTS AND METHODS

Between 1990 and 2000, 90 patients were diagnosed as having a pyloric gland adenoma in the stomach (77 patients), duodenal bulb (7 patients), duodenum (1 patient), bile duct (3 patients) or gallbladder (2 patients).

RESULTS

Pyloric gland adenomas account for 2.7% of all gastric polyps and occur predominantly in old age (73+/-12.8 years), more frequently in women (75%) than in men. The predilection site in the stomach is the corpus mucosa (64%) and they are often found in patients suffering from autoimmune gastritis (36%). At the time of diagnosis, pyloric gland adenomas measure 16.1+/-9.1 mm in size. In 30% of gastric pyloric adenomas, transition to well-differentiated adenocarcinoma has been noted.

DISCUSSION

In our material, pyloric gland adenoma is the third most common neoplastic polypoid lesion in the stomach. Since a search through the literature revealed only a few case reports on this lesion, it is possible that for some reason this lesion might be diagnosed more often than reported.

CONCLUSION

Our study revealed that 30% of the gastric pyloric gland adenomas showed continuous transition to well-differentiated adenocarcinoma at the time of the initial diagnosis. This underscores the malignant potential of the lesion, and the need for polypectomy.