Pyloric gland adenoma: an entity distinct from gastric foveolar type adenoma. Am J Surg Pathol. 2009;33:186-193. [PMID: 18830123 DOI: 10.1097/pas.0b013e31817d7ff4]

[Gastric adenoma of pyloric type associated with familial adenomatous polyposis: A rare histological type not to be overlooked]

We report here two cases of gastric adenomas of pyloric type diagnosed during the follow-up of familial adenomatous polyposis (FAP). This rare histological lesion has been only recently described in this particular context and its clinical and pathological spectrum remains to be evaluated. Our two cases were very different in their clinical and endoscopic presentation. In the first patient, the lesion was diagnosed late during the evolution of FAP; it was very large and protruded above the adjacent mucosa; because of its large size, its treatment proved to be difficult. In the second patient, the lesion was discovered incidentally in gastric biopsies, early in the course of FAP. Both lesions presented the characteristic morphological and immunohistochemical features of pyloric adenoma, including the expression of MUC6. Both showed evidence of dysplasia, including high-grade dysplasia in the largest lesion. Pyloric adenoma belongs to the spectrum of gastric polyps associated with FAP; its prognosis and evolution remain to be evaluated.

Practical Points in Gastric Pathology

CONTEXT

-The diagnosis of gastric epithelial lesions is difficult in clinical practice, even with the recent developments and advances in endoscopic modalities, owing to the diverse morphologic features of the lesions, lack of standardized diagnostic criteria, and the high intraobserver and interobserver variabilities in the nonneoplastic (regenerative)-neoplastic spectrum.

OBJECTIVE

-To provide an overview of the current concepts and unresolved issues surrounding the diagnosis of diseases in the nonneoplastic-neoplastic spectrum, and to discuss some noteworthy properties and histologic features of gastric epithelial lesions.

DATA SOURCES

-A comprehensive assessment of the medical literature on gastric epithelial lesions was performed; we also interjected our own experiences into the discussion. Sources included original studies, review articles, and textbooks related to the field.

CONCLUSIONS

-Our literature review revealed that clear cell changes and micropapillary carcinoma components in gastric carcinomas are associated with poor clinical outcomes and should hence be included in pathologic reports. Moreover, we suggest a stepwise biopsy-endoscopic resection modality for the diagnosis of borderline neoplasia-nonneoplasia cases.

Patients with McCune-Albright syndrome have a broad spectrum of abnormalities in the gastrointestinal tract and pancreas

McCune-Albright Syndrome (MAS) is a rare sporadic syndrome caused by post-zygotic mutations in the GNAS oncogene, leading to constitutional mosaicism for these alterations. Somatic activating GNAS mutations also commonly occur in several gastrointestinal and pancreatic neoplasms, but the spectrum of abnormalities in these organs in patients with MAS has yet to be systematically described. We report comprehensive characterization of the upper gastrointestinal tract in seven patients with MAS and identify several different types of polyps, including gastric heterotopia/metaplasia (7/7), gastric hyperplastic polyps (5/7), fundic gland polyps (2/7), and a hamartomatous polyp (1/7). In addition, one patient had an unusual adenomatous lesion at the gastroesophageal junction with high-grade dysplasia. In the pancreas, all patients had endoscopic ultrasound findings suggestive of intraductal papillary mucinous neoplasm (IPMN), but only two patients met the criteria for surgical intervention. Both of these patients had IPMNs at resection, one with low-grade dysplasia and one with high-grade dysplasia. GNAS mutations were identified in the majority of lesions analyzed, including both IPMNs and the adenomatous lesion from the gastroesophageal junction. These studies suggest that there is a broad spectrum of abnormalities in the gastrointestinal tract and pancreas in patients with MAS and that patients with MAS should be evaluated for gastrointestinal pathology, some of which may warrant clinical intervention due to advanced dysplasia.

Morphology and genetics of pyloric gland adenomas in familial adenomatous polyposis

AIMS

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

METHODS AND RESULTS

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

CONCLUSION

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

Pathology and Genetics of Syndromic Gastric Polyps

Gastric polyps are found in 1% to 4% of patients undergoing gastroscopy. The vast majority are sporadic, but some gastric polyps indicate an underlying syndrome. Gastric polyps can manifest in each of the gastrointestinal polyposis syndromes, including the recently described gastric adenocarcinoma and proximal polyposis of the stomach syndrome. In addition, gastric polyps occur in Lynch syndrome and in a few rare conditions that are not primarily gastrointestinal. While some of these syndromes are clearly associated with an increased risk of gastric cancer, others are not. Interestingly, even in disorders with a well-established risk of gastric cancer, the neoplastic potential and the precursor status of these gastric polyps are not always clear. Although rare, recognition of syndromic gastric polyps is important for individual patient management. These conditions also serve as important models to study gastric homeostasis and gastric tumorigenesis.

Autoimmune Metaplastic Atrophic Gastritis: Recognizing Precursor Lesions for Appropriate Patient Evaluation

Autoimmune metaplastic atrophic gastritis (AMAG) is a significant risk factor for pernicious anemia and gastric neoplasia. Still, the histologic features of AMAG are frequently overlooked, especially in the early stages of the disease. The purpose of our study, therefore, was to catalogue the progression of histologic changes that precede the development of AMAG in affected individuals. Over a 2-year period (2012 to 2014), the diagnosis of AMAG was rendered on material from 113 patients seen at Johns Hopkins Hospital (∼1.8% of "in house" gastric biopsies). Prior gastric body biopsies had been performed on 54 (48%) patients in the cohort, and the majority of these specimens had also shown AMAG. Eighteen of the previous biopsies, however, carried a diagnosis other than AMAG: 13 inactive chronic gastritis, 2 acute Helicobacter pylori gastritis, and 1 each of eosinophilic gastritis, iron pill gastritis, and proton-pump inhibitor-like effect. Upon review of these 18 biopsies, the most common histologic findings were heavy full-thickness or deep lamina propria chronic inflammation (12), inflammatory destruction of oxyntic glands (12), metaplasia (intestinal, pyloric, or pancreatic acinar) (10), prominent lamina propria eosinophils (8), and parietal cell pseudohypertrophy (4). At least 2 of these features were present in the majority (13, 72%) of the biopsies. In addition, 7 (58%) of these patients were also found to have another autoimmune or inflammatory disorder before the diagnosis of AMAG. Although subtle, histologic features of developing AMAG are identifiable in routine gastric body biopsies. When metaplasia, full-thickness chronic inflammation, and/or oxyntic destruction are seen, a note suggesting laboratory testing and/or close clinical follow-up in this subset of patients may be warranted.

Tubular Pyloric Gland Adenoma of the Left and Right Hepatic Ducts: Report of a Unique Case With Immunohistochemical and Molecular Studies

Pyloric gland adenomas (PGAs) of the extrahepatic biliary system are rare lesions. We report a case of a tubular PGA that led to biliary obstruction. The tumor was located at the confluence of the right and left hepatic ducts, extending to the left hepatic duct. The tumor cells expressed MUC6 and MUC5AC. MUC1 and CD10 were focally positive. MUC2, p53, and CDX2 were not expressed. The Ki67 positivity was estimated at <15%. None of the KRAS, NRAS, BRAF, EGFR coding regions resulted in clinically relevant amino acid substitutions. SNP rs1050171 (EGFR p.Q787Q, silent mutation) corresponding to c.2361G>A transition in exon 20 was noticed. Awareness of this rare lesion is important for pathologists and clinicians alike, because it may cause significant morphologic and clinical difficulties, especially when presenting as an obstructive mass. Because of the possible risk of evolving malignancy, surgical resection is recommended whenever possible.

Autoimmune gastritis: Pathologist's viewpoint

Western countries are seeing a constant decline in the incidence of Helicobacter pylori-associated gastritis, coupled with a rising epidemiological and clinical impact of autoimmune gastritis. This latter gastropathy is due to autoimmune aggression targeting parietal cells through a complex interaction of auto-antibodies against the parietal cell proton pump and intrinsic factor, and sensitized T cells. Given the specific target of this aggression, autoimmune gastritis is typically restricted to the gastric corpus-fundus mucosa. In advanced cases, the oxyntic epithelia are replaced by atrophic (and metaplastic) mucosa, creating the phenotypic background in which both gastric neuroendocrine tumors and (intestinal-type) adenocarcinomas may develop. Despite improvements in our understanding of the phenotypic changes or cascades occurring in this autoimmune setting, no reliable biomarkers are available for identifying patients at higher risk of developing a gastric neoplasm. The standardization of autoimmune gastritis histology reports and classifications in diagnostic practice is a prerequisite for implementing definitive secondary prevention strategies based on multidisciplinary diagnostic approaches integrating endoscopy, serology, histology and molecular profiling.

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.

Decreased expression of gastric gland mucin-specific glycan α1,4-linked N-acetylglucosamine on its scaffold mucin 6 is associated with malignant potential of pyloric gland adenoma of the stomach

AIMS

Pyloric gland adenoma (PGA) is a unique gastric neoplasm expressing mucin 6 (MUC6), and is often associated with high-grade dysplasia and/or adenocarcinoma. MUC6 secreted from the gastric gland mucous cells, such as pyloric gland cells, carries unique O-glycans with terminal α1,4-linked N-acetylglucosamine (αGlcNAc) residues on its molecule. As we recently demonstrated that αGlcNAc serves as a tumour suppressor for gastric adenocarcinoma, this study aimed to investigate the significance of αGlcNAc expression in PGA.

METHODS AND RESULTS

Eighteen patients with PGA were examined with immunohistochemistry for αGlcNAc and MUC6. αGlcNAc and MUC6 were coexpressed in 12 of 18 PGAs. However, reduced αGlcNAc expression relative to MUC6 expression was observed in six cases. When the MIB-1 labelling index (LI) of tumour cells was examined with respect to reduced αGlcNAc expression, the MIB-1 LI was significantly higher in PGAs showing decreased αGlcNAc expression relative to MUC6 expression than in PGAs with unchanged αGlcNAc expression (P = 0.023).

CONCLUSIONS

The present study indicates that coexpression of αGlcNAc and MUC6 in PGA suggests the presence of fully glycosylated MUC6 on tumour cells, consistent with pyloric gland differentiation. However, the decreased glycosylation of αGlcNAc on MUC6 is associated with high mitotic activity of tumour cells, indicative of malignant potential of PGA.

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.

Gastric adenocarcinoma of the fundic gland type shares common genetic and phenotypic features with pyloric gland adenoma

Gastric adenocarcinoma of the fundic gland type (GAFG) and pyloric gland adenoma (PGA) have recently been recognized as rare types of neoplasia. We performed comparative immunohistochemical and genetic analyses of 3 GAFGs and 12 PGAs. All of the 3 GAFGs were diffusely positive for pepsinogen-I, MIST1 and MUC6, indicating the predominantly chief cell/mucous neck cell differentiation of these tumors. A small number of H.K-ATPase-positive parietal cells were also scattered. PGAs invariably exhibited diffuse MUC6 and TFF2 expression, consistent with the pyloric gland differentiation of these tumors. Ten of the 12 PGAs also unexpectedly exhibited focal expression of pepsinogen-I and MIST1, suggesting that PGAs often show focal chief cell differentiation and phenotypically resemble mucous neck cells rather than pyloric glands. The mutation analyses revealed activating GNAS mutations, which have been reported to be frequently detected in PGAs, in two of the GAFGs. While GAFGs and PGAs are morphologically distinct lesions, our observations showed their partially overlapping immunohistochemical profiles and shared presence of GNAS mutations, in addition to their common occurrence in the fundic gland mucosa. Based on these observations, we suggest that both GAFGs and PGAs are closely related lesions characterized by a mucous neck cell/chief cell lineage phenotype.

Mitochondrial DNA alterations in the progression of gastric carcinomas: unexplored issues and future research needs

Gastric cancer is the second most frequent cause of cancer death worldwide. Patients infected with Helicobacter pylori (H. pylori) are at increased risk of gastric cancer. H. pylori induces genomic instability in both nuclear and mitochondrial (mt) DNA of gastric epithelial cells. Changes in mtDNA represent an early event during gastric tumorigenesis, and thus may serve as potential biomarkers for early detection and prognosis in gastric carcinoma.This review article summarizes the mtDNA mutations that have been reported in gastric carcinomas and their precancerous conditions. Unexplored research topics, such as the role of mtDNA alterations in an alternative pathway of gastric carcinogenesis, are identified and directions for future research are suggested.

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.

Upper GI tract lesions in familial adenomatous polyposis (FAP): enrichment of pyloric gland adenomas and other gastric and duodenal neoplasms

Patients with familial adenomatous polyposis (FAP), an autosomal dominant cancer predisposition syndrome caused by mutations in the APC gene, develop neoplasms in both the upper and lower gastrointestinal (GI) tract. To clarify the upper GI tract lesions in FAP patients in a tertiary care setting, we reviewed specimens from 321 endoscopies in 66 patients with FAP. Tubular adenomas in the small bowel were the most common neoplasms (present in 89% of patients), although only 1 patient developed invasive carcinoma of the small bowel. Several types of gastric neoplasms were identified--65% of patients had at least 1 fundic gland polyp, and 23% of patients had at least 1 gastric foveolar-type gastric adenoma. Pyloric gland adenomas were also enriched, occurring in 6% of patients--this is a novel finding in FAP patients. Despite the high frequency of gastric neoplasms, only 1 patient developed carcinoma in the stomach. The very low frequency of carcinoma in these patients suggests that current screening procedures prevent the vast majority of upper GI tract carcinomas in patients with FAP, at least in the tertiary care setting.

Pyloric gland adenoma: a case report

Endoscopic procedures are the gold standard in identifying, monitoring and treating gastrointestinal system lesions. The evaluation of benign, precancerous and malignant characteristics of these lesions requires good endoscopic inspection and precise pathological examination. Pyloric gland adenoma is a rare precancerous lesion defined in recent years and herein is reviewed in the present case along with the literature.

Autoimmune atrophic gastritis--pathogenesis, pathology and management

Autoimmune gastritis is a chronic progressive inflammatory condition that results in the replacement of the parietal cell mass by atrophic and metaplastic mucosa. A complex interaction of autoantibodies against the parietal cell proton pump and sensitized T cells progressively destroy the parietal cells, inducing hypochlorhydria and then achlorhydria, while autoantibodies against the intrinsic factor impair the absorption of vitamin B₁₂. The resulting cobalamin deficiency manifests with megaloblastic anaemia and neurological and systemic signs and symptoms collectively known as pernicious anaemia. Previously believed to be predominantly a disease of elderly women of Northern European ancestry, autoimmune gastritis has now been recognized in all populations and ethnic groups, but because of the complexity of the diagnosis no reliable prevalence data are available. For similar reasons, as well as the frequent and often unknown overlap with Helicobacter pylori infection, the risk of gastric cancer has not been adequately assessed in these patients. This Review summarizes the epidemiology, pathogenesis and pathological aspects of autoimmune metaplastic atrophic gastritis. We also provide practical advice for the diagnosis and management of patients with this disease.

Pathology of gastric cancer and its precursor lesions

Gastric cancers are a histologically heterogenous group of neoplasms arising from unique epidemiologic and molecular backgrounds. There is accumulating evidence that the intestinal type of gastric adenocarcinoma develops through a multistep process beginning with chronic gastritis triggered primarily by Helicobacter pylori and progressing through atrophy, intestinal metaplasia, and dysplasia (intraepithelial neoplasia) to carcinoma. Loss of E-cadherin expression resulting from CDH1 gene alterations is the primary carcinogenetic event in hereditary diffuse gastric cancer. Proximal gastric adenocarcinomas likely result from either gastroesophageal reflux or H pylori gastritis. This article provides an update of the histologic, immunohistochemical, and molecular pathways of gastric cancer and its precursors.

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.

Adenocarcinoma with pyloric gland phenotype of the extrahepatic bile ducts: a previously unrecognized and distinctive morphologic variant of extrahepatic bile duct carcinoma

Carcinomas of the extrahepatic bile ducts are uncommon and morphologically heterogeneous. We report 3 unique examples of adenocarcinomas that show predominantly pyloric gland differentiation (80%-100%) and compare their immunohistochemical profile with that of pyloric gland adenomas of the gallbladder, foveolar, and intestinal-type adenocarcinomas of the extrahepatic bile duct. The 3 patients with pyloric gland adenocarcinomas were younger than those with conventional adenocarcinomas. The 3 tumors were very well differentiated but showed extensive perineural invasion. They consisted of a variable proportion of small, medium-sized, and cystically dilated glands separated by abundant desmoplastic stroma. The glands were lined by columnar cells with abundant mucin-containing cytoplasm and small hyperchromatic basally placed nuclei with inconspicuous nucleoli. A characteristic feature of these pyloric gland adenocarcinomas was that the glands had a stellar pattern that was not seen in foveolar-, intestinal-, or biliary-type adenocarcinomas. Two pyloric gland adenocarcinomas coexpressed MUC6 and MUC5AC. The diffuse pattern of reactivity of MUC5AC and MUC6 was similar to that of 10 pyloric gland adenomas of the gallbladder and 2 foveolar adenocarcinomas of the extrahepatic bile duct. In contrast, 5 intestinal adenocarcinomas of the extrahepatic bile duct labeled with the intestinal marker CDX2 and 3 with the colonic MUC2 but were negative for MUC6 and MUC5AC. We believe that these pyloric gland adenocarcinomas represent a previously unrecognized distinct clinicopathologic entity. Despite their deceptively benign microscopic appearance, 1 patient died with local recurrence and liver metastasis, another patient is living with tumor, and the third patient is asymptomatic but only 5 months after surgery.

Intracholecystic papillary-tubular neoplasms (ICPN) of the gallbladder (neoplastic polyps, adenomas, and papillary neoplasms that are ≥1.0 cm): clinicopathologic and immunohistochemical analysis of 123 cases

The literature on the clinicopathologic characteristics of tumoral intraepithelial neoplasms (neoplastic polyps) of the gallbladder (GB) is fairly limited, due in part to the variability in definition and terminology. Most reported adenomas (pyloric gland type and others) were microscopic and thus regarded as clinically inconsequential, whereas papillary in situ carcinomas have been largely considered a type of invasive adenocarcinoma under the heading of "papillary adenocarcinomas." In this study, 123 GB cases that have a well-defined exophytic preinvasive neoplasm measuring ≥1 cm were analyzed. The patients were predominantly female (F/M=2:1) with a mean age of 61 y and a median tumor size of 2.2 cm. Half of the patients presented with pain, and in the other half the neoplasm was detected incidentally. Other neoplasms, most being gastrointestinal tract malignancies, were present in 22% of cases. Gallstones were identified in only 20% of cases. Radiologically, almost half were diagnosed as "cancer," roughly half with polypoid tumor, and in 10% the lesion was missed. Pathologic findings: (1) The predominant configuration was papillary in 43%, tubulopapillary in 31%, tubular in 26%. (2) Each case was assigned a final lineage type on the basis of the predominant pattern (>75% of the lesion) on morphology, and supported with specific immunohistochemical cell lineage markers. The predominant cell lineage could be identified as biliary in 50% (66% of which were MUC1), gastric foveolar in 16% (all were MUC5AC), gastric pyloric in 20% (92% MUC6), intestinal in 8% (100% CK20; 75% CDX2; 50%, MUC2), and oncocytic in 6% (17% HepPar and 17% MUC6); however, 90% of cases had some amount of secondary or unclassifiable pattern and hybrid immunophenotypes. (3) Of the cases that would have qualified as "pyloric gland adenoma," 21/24 (88%) had at least focal high-grade dysplasia and 18% had associated invasive carcinoma. Conversely, 8 of 47 "papillary adenocarcinoma"-type cases displayed some foci of low-grade dysplasia, and 15/47 (32%) had no identifiable invasion. (4) Overall, 55% of the cases had an associated invasive carcinoma (pancreatobiliary type, 58; others, 10). Factors associated significantly with invasion were the extent of high-grade dysplasia, cell type (biliary or foveolar), and papilla formation. Among systematically analyzed invasive carcinomas, tumoral intraepithelial neoplasia was detected in 6.4% (39/606). (5) The 3-year actuarial survival was 90% for cases without invasion and 60% for those associated with invasion. In contrast, those associated with invasion had a far better clinical outcome compared with pancreatobiliary-type GB carcinomas (3-yr survival, 27%), and this survival advantage persisted even with stage-matched comparison. Death occurred in long-term follow-up even in a few noninvasive cases (4/55; median 73.5 mo) emphasizing the importance of long-term follow-up. In conclusion, tumoral preinvasive neoplasms (≥1 cm) in the GB are analogous to their pancreatic and biliary counterparts (biliary intraductal papillary neoplasms, pancreatic intraductal papillary mucinous neoplasms, and intraductal tubulopapillary neoplasms). They show variable cellular lineages, a spectrum of dysplasia, and a mixture of papillary or tubular growth patterns, often with significant overlap, warranting their classification under 1 unified parallel category, intracholecystic papillary-tubular neoplasm. Intracholecystic papillary-tubular neoplasms are relatively indolent neoplasia with significantly better prognosis compared with pancreatobiliary-type GB carcinomas. In contrast, even seemingly innocuous examples such as those referred to as "pyloric gland adenomas" can progress to carcinoma and be associated with invasion and fatal outcome.

Adenomas of the gallbladder. Morphologic features, expression of gastric and intestinal mucins, and incidence of high-grade dysplasia/carcinoma in situ and invasive carcinoma

We report 201 gallbladder adenomas from 91 patients most of whom were adult females. Fifty-three (58%) patients had gallstones. In 83 (91%) patients the adenomas were single. One gallbladder had 102 adenomas. Histologically, 165 (82%) of 201 adenomas were classified as pyloric, 28 (14%) as intestinal, 5 (2.4%) as foveolar, and 3 (1.4%) as biliary. Two patients had intestinal-type adenomas coexisting with biliary papillomatosis. Twenty-eight percent of pyloric gland adenomas contained squamoid morules. Two pyloric gland adenomas were composed predominantly of columnar oxyphil cells. High-grade dysplasia/carcinoma in situ was identified in 44 (27%) of 165 pyloric gland adenomas and low-grade dysplasia in 25 (15%) of 165. However, only 2 (1%) invasive adenocarcinomas, both of intestinal type, arose in pyloric gland adenomas. Both patients survived more than 5 years. Intestinal-type adenomas were classified as tubular, papillary, and tubulopapillary. High-grade dysplasia/carcinoma in situ was recognized in 13 (46%) of 28 intestinal adenomas. However, only 1 (3.5%) invasive adenocarcinoma with biliary phenotype arose in an intestinal-type adenoma. Foveolar adenomas showed low-grade dysplasia, and biliary adenomas were composed of columnar cells similar to the normal biliary cells of the gallbladder. None of these tumors progressed to adenocarcinoma. MUC5AC and MUC6 labeled 44 (95%) of 46 pyloric gland adenomas, whereas CDX2 was positive in 14 (78%) of 18 intestinal adenomas and MUC2 in 6 (33%) of 18. MUC5AC and MUC6 labeled 2 foveolar adenomas, and 2 biliary adenomas expressed only CK7. The immunophenotype of gallbladder adenomas justifies their classification into pyloric, intestinal, foveolar, and biliary. Our results indicate that adenomas of the gallbladder play a minor role in the pathway of gallbladder carcinogenesis.

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.

Gastric lesions in patients with autoimmune metaplastic atrophic gastritis (AMAG) in a tertiary care setting

Autoimmune metaplastic atrophic gastritis (AMAG) is an early manifestation of pernicious anemia that precedes the hematologic changes by years to decades. It is associated with metaplastic changes and neoplasms, including pyloric gland adenomas (PGAs). We investigated the frequency of PGAs and other lesions in all nonconsultation gastric biopsies and resections (1988 to 2008) diagnosed as AMAG. We further selected cases confirmed as AMAG by immunohistochemical identification of the gastric body (negative gastrin) and linear and nodular enterochromaffin-like cell hyperplasia (chromogranin). From this subset, all polyps and neoplasms were reviewed. We identified a total of 41,245 patients with gastric biopsies or resections from 46.7% males and 53.3% females comprising patients self-identified as 67.0% white, 23.6% African-American, 1.4% Asian, 0.8% non-White Hispanic, and 7.2% other or unknown. AMAG was diagnosed in 461 patients (1.1%), and had the following percentages based on race: 1.1% White, 1.3% African-American, 1.4% Asian, and 2.7% non-White Hispanic. The female:male ratio was 2:1 with an overall median age at presentation of 67.0 years. Of the 461 patients with AMAG, 143 had endoscopically identifiable lesions. These lesions (n=240) consisted of 179 polyps (138 hyperplastic polyps, 20 oxyntic mucosa pseudopolyps, 18 intestinal-type gastric adenomas, and 3 PGAs), 46 well-differentiated neuroendocrine neoplasms (carcinoid), 1 gastrointestinal stromal tumor, 3 lymphomas, and 11 adenocarcinomas. In summary, AMAG occurred with similar frequency across all racial groups. Although PGAs are associated with AMAG, they remain rare in the setting of AMAG.

Loss of cell polarity protein Lgl2 in foveolar-type gastric dysplasia: correlation with expression of the apical marker aPKC-zeta

Recognition of gastric epithelial dysplasia, although a key to cancer prevention, can be challenging. In this study, we evaluated whether Lgl2 can serve as a marker of gastric foveolar-type dysplasia. Since atypical protein kinase C (aPKC) is a partner of Lgl2 in the control of apical-basal polarity we also investigated whether aPKC-zeta can compliment Lgl2 as a marker of dysplasia. Routinely processed specimens included 64 normal mucosa, 35 reactive gastropathies, 31 chronic gastritides, 65 gastric dysplasias (25 foveolar; 40 adenomatous), and 34 gastric adenocarcinomas. Twenty (80%) foveolar-type dysplasias showed absence of Lgl2 immunoreactivity, while normal basolateral expression of Lgl2 was consistently seen in normal gastric epithelium (n=20) and chronic gastritis (n=22; p<0.00001). Loss of Lgl2 was similar in the groups with low-grade and high-grade foveolar-type dysplasia, 79% and 83%, respectively. Linear apical anti-aPKC-zeta immunoreactivity was consistently present in the normal epithelium and was preserved in 91% of reactive gastropathies and 87% of chronic gastritides. In contrast, loss of apical aPKC-zeta staining was observed in 47% and 65% of low-grade dysplasias of foveolar and adenomatous types, respectively (p<0.005) and in nonsignificantly higher percentage of high-grade dysplasias. Apical aPKC-zeta staining was lost in 97% of gastric adenocarcinomas. Our data suggest a role of Lgl2 immunohistochemistry as an adjunct in the diagnosis of foveolar-type gastric dysplasia. aPKC-zeta had moderate sensitivity as a marker of gastric dysplasia and additional studies are needed to establish its role in the diagnosis of dysplasia.

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.

Neoplasia without dysplasia: lessons from Barrett esophagus and other tubal gut neoplasms

CONTEXT

Classic pathology teaching emphasizes that neoplastic lesions of the gastrointestinal tract are characterized by architectural and cytologic abnormalities that distinguish it from normal tissue. Recent studies suggest that many important-and in some cases clonal-molecular abnormalities that lead to dysregulation of cell proliferation and differentiation (neoplasia) occur before morphologic expression of dysplasia.

OBJECTIVE

To summarize the biologic and pathologic features of preneoplastic conditions of the tubal gut that reveal evidence of neoplastic alteration, but without the traditional morphologic features of dysplasia, in order to provide guidance on how to identify these lesions. Particular attention is given to Barrett esophagus, a chronic inflammatory condition in which early molecular and morphologic events that drive carcinogenesis are best understood.

DATA SOURCES

Selected references and abstracts were obtained by a PubMed (US National Library of Medicine) search by using the search headings neoplasia, preneoplasia, dysplasia, adenoma, serrated polyps, and Barrett's esophagus between the years 1980 and 2009.

CONCLUSIONS

Many types of lesions throughout the tubal gut fulfill the most basic and classic principles of a neoplastic precursor lesion but lack conventional morphologic evidence of dysplasia and/or maintain the capacity for cell differentiation and maturation. All of these lesions, such as squamous dysplasia of the esophagus, dysplasia in Barrett esophagus, and hyperplastic/serrated polyps of the colon, represent early neoplastic precursor lesions but without conventional histologic features of dysplasia. It is important for pathologists to be aware of these lesions, both for diagnostic and prognostic purposes, but also so that future studies can be performed with regard to risk stratification of patients.