Akiko Matsubara

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.

Prevalence of MED12 mutations in uterine and extrauterine smooth muscle tumours.

To determine the prevalence of MED12 mutations in smooth muscle tumours of different organs.

Re-evaluation of Histogenesis of Gastric Carcinomas: A Comparative Histopathological Study Between Helicobacter pylori-Negative and H. pylori-Positive Cases

We histopathologically re-evaluated the histogenesis of gastric carcinomas from comparative studies between Helicobacter pylori-positive and H. pylori-negative cases using the gastritis score from the Updated Sydney System. The incidence of H. pylori-negative gastric carcinomas was 3.11% (12/386); they are likely to develop in the fundic gland mucosa, and show a gastric phenotype by mucin immunohistochemistry. Even in cases of completely gastric and predominantly gastric phenotypes, CDX2 protein was expressed in most cases (90.9% of pT1 and 100% of pT2-3), indicating a possibility that intestinalization of carcinoma cells occurs independently of the background mucosa. Regarding the degree of gastritis of background mucosa surrounding 143 H. pylori-positive differentiated-type adenocarcinomas, the mean score ranged from 1.497 to 1.713. Our data support the hypothesis that intestinal metaplasia is not a precancerous but a paracancerous lesion, and most gastric adenocarcinomas develop in mildly to moderately atrophic mucosa with H. pylori-infection, i.e., ongoing atrophy.

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.

Lobular endocervical glandular hyperplasia is a neoplastic entity with frequent activating GNAS mutations.

To clarify the significance of GNAS mutations in cervical tumorigenesis, we performed mutational analyses in a total of 154 lesions and in 22 normal tissues of the uterine cervix. Activating GNAS mutations were found in 8 of the 19 lobular endocervical glandular hyperplasias (LEGH; 42%) and 4 of the 79 endocervical-type mucinous adenocarcinomas (5%) but were never seen in the normal endocervical tissue, minimal deviation adenocarcinomas, endometrioid adenocarcinomas, or squamous cell carcinomas. We further examined the presence of human papillomavirus (HPV) DNA and p16 expression to probe the relationship between GNAS mutations and HPV infection in LEGHs and carcinomas. All the GNAS-mutated LEGHs were negative for HPV DNA and p16 expression, whereas all the GNAS-mutated adenocarcinomas were positive for HPV DNA and/or p16 expression, implicating GNAS mutations in the development of LEGH and a minor subset of HPV-related cervical adenocarcinomas. Additional mutational analyses of LEGH identified KRAS and STK11 mutations in 1 and 2 cases, respectively. The GNAS, KRAS, and STK11 mutations were mutually exclusive; thus, a total of 11 LEGHs (58%) had 1 of these genetic alterations. Although LEGH has been regarded as a metaplastic lesion, the frequent presence of genetic alterations suggests a neoplastic nature.

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

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.

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.

Different histological status of gastritis in superficial adenocarcinoma of the esophagogastric junction.

OBJECTIVE Although many gastric cancers arise in chronic gastritis, the association between adenocarcinoma of the esophagogastric junction and the status of background gastritis remains unclear. We aim to investigate the histological status of gastritis in the background fundic gland mucosa of adenocarcinoma of the esophagogastric junction. METHODS The present study included 121 consecutive patients with superficial adenocarcinoma of the esophagogastric junction obtained by surgical and/or endoscopic resection. We re-evaluated the histogenesis of adenocarcinoma of the esophagogastric junction, including the background fundic gland mucosa using the Updated Sydney System. The prevalence of histologic atrophic gastric mucosa with gastritis (positive gastritis), non-atrophic gastric mucosa without gastritis (negative gastritis) and Barretts adenocarcinoma was examined. RESULTS Histologic-positive gastritis was found in 67 (55%) of all patients, in 24 (38%) of 63 Barretts adenocarcinoma patients and in 43 (74%) of 58 non-Barretts adenocarcinoma patients (P < 0.01). A higher female ratio in non-Barretts adenocarcinoma with gastritis patients `and younger age in non-Barretts adenocarcinoma without gastritis patients were shown. There were no differences in clinicopathological features related to the gastritis status in Barretts adenocarcinoma patients. Reflux esophagitis was observed in most (81%) of all patients, and 32 (74%) of the non-Barretts adenocarcinoma with gastritis patients. In the 67 positive gastritis patients, the mean Updated Sydney System scores of glandular atrophy and intestinal metaplasia were 1.45 and 1.10, respectively, and these scores were higher in the non-Barretts adenocarcinoma patients than in the Barretts adenocarcinoma patients. CONCLUSIONS This study suggests that about half of the patients with adenocarcinoma of the esophagogastric junction harbor histological gastritis. Adenocarcinoma of the esophagogastric junction is considered to be a heterogeneous entity, including Barretts esophagus-related, positive gastritis-related, and Barretts esophagus and gastritis-unrelated adenocarcinoma of the esophagogastric junction.

Intraductal dissemination of papillary adenocarcinoma of the ampulla of Vater in the pancreatic duct.

It has been speculated that intraductal dissemination, via the pancreatic duct, bile duct, or mammary duct, is a unique form of cancer cell spread. However, clinical evidence to confirm this form of dissemination has been lacking. Here we report a case of papillary adenocarcinoma of the ampulla of Vater in which retrograde dissemination to the pancreatic duct was strongly suggested. A 79‐year‐old woman underwent pancreatoduodenectomy for a 22 mm microinvasive papillary adenocarcinoma of the ampulla. Multiple carcinomas in situ were found in the pancreatic duct distant from the ampulla. Seven months later, she underwent a second operation for a recurrent papillary adenocarcinoma at the pancreato‐jejunal anastomosis showing exophytic and expansive growth into the jejunal lumen that connected to an intraductal adenocarcinoma in the pancreatic body. None of these tumors showed invasive growth, or vascular or neural invasion, being separate from each other but sharing identical histological, immunohistochemical, and molecular features; papillary growth, a pancreatobiliary phenotype, the same pattern of genomic loss of heterozygosity, and no mutation of the KRAS, TP53, and GNAS genes. These results imply that this papillary adenocarcinoma of the ampulla of Vater had disseminated to the pancreatic duct in a retrograde manner and recurred in the remnant pancreas.

Fulminant pseudomembranous enterocolitis caused by Klebsiella oxytoca: an autopsy case report

We describe a rare case of antibiotic‐associated fulminant pseudomembranous enterocolitis caused by Klebsiella oxytoca. A 79‐year‐old man with a history of antibiotic therapy was admitted to our emergency department, complaining of consciousness disturbance. Initially, we suspected septic shock and diabetic ketoacidosis caused by intestinal infection. Although we administered sufficient extracellular fluid, his blood pressure was not elevated and his abdomen gradually swelled.