The syndrome of gastric argyrophil carcinoid tumors and nonantral gastric atrophy

Gastric carcinoids: Does type of surgery or tumor affect survival?

BACKGROUND

Gastric carcinoids are rare neuroendocrine tumors of the gastrointestinal tract. They are typically managed according to their etiology. However, there is little known about the impact of surgical strategy on the long-term outcomes of these patients.

METHODS

All patients who underwent resection of gastric carcinoids at 8 institutions from 2000 to 2016 were analyzed retrospectively. Tumors were stratified according to subtype (I, II, III, IV) and resection type (local resection, LR or formal gastrectomy, FG). Clinicopathological parameters, recurrence-free (RFS) and overall survival (OS) were compared between groups.

RESULTS

Of 79 patients identified with gastric carcinoids, 34 had type I lesions associated with atrophic gastritis, 4 had type II lesions associated with a gastrinoma, 37 had type III sporadic lesions, and 4 had type IV poorly-differentiated lesions. The mean age of presentation was 56 years in predominantly Caucasian (77%) and female (63%) patients. Mean tumor size was 2.4 cm and multifocal tumors were found in 24 (30%) of patients with the majority occurring in those with type I tumors. Lymph node positive tumors were seen in 15 (19%) patients and 7 (8%) had M1 disease; both most often in type IV followed by type III tumors. R0 resection was achieved in 56 (71%) patients while 15 (19%) had R1 resections and 6 (8%) R2 resections. Patients with type I and III tumors were equally likely to have a LR (50% and 43% respectively) compared to FG while those with type II and IV all had FG with one exception. Type IV tumors had the poorest RFS and OS while Type II tumors had the most favorable RFS and OS (p < 0.04 and p < 0.0004, respectively). While there was no difference in RFS in those patients undergoing FG versus LR, OS was worse in the FG group (p < 0.017). This trend persisted when type II and type IV groups were excluded (p < 0.045).

CONCLUSION

Gastric carcinoid treatment should be tailored to tumor type, as biologic behavior rather than resection technique is the more important factor contributing to long-term outcomes.

Multiple Gastric Carcinoids and Pernicious Anemia: Report of a Case

A case of pernicious anemia associated with multiple gastric carcinoids is reported. The neoplastic growth was composed of enterochromaffin-like (ECL) cells, and ECL cell hyperplasia was observed also in hyperplastic polyps, inside the fundic glands and in small nests lying in the lamina propria (microcarcinoidosis). The possible relation between pernicious anemia and ECL cell hyperplasia is discussed.

Prognostic Evaluations Tailored to Specific Gastric Neuroendocrine Neoplasms: Analysis Of 200 Cases with Extended Follow-Up

BACKGROUND

Gastric neuroendocrine neoplasms (NENs) are very heterogeneous, ranging from mostly indolent, atrophic gastritis-associated, type I neuroendocrine tumors (NETs), through highly malignant, poorly differentiated neuroendocrine carcinomas (pdNECs), to sporadic type III NETs with intermediate prognosis, and various rare tumor types. Histologic differentiation, proliferative grade, size, level of gastric wall invasion, and local or distant metastases are used as prognostic markers. However, their value remains to be tailored to specific gastric NENs.

METHODS

Series of type I NETs (n = 123 cases), type III NETs (n = 34 cases), and pdNECs (n = 43 cases) were retrospectively collected from four pathology centers specializing in endocrine pathology. All cases were characterized clinically and histopathologically. During follow-up (median 93 months) data were recorded to assess disease-specific patient survival.

RESULTS

Type I NETs, type III NETs, and pdNECs differed markedly in terms of tumor size, grade, invasive and metastatic power, as well as patient outcome. Size was used to stratify type I NETs into subgroups with significantly different invasive and metastatic behavior. All 70 type I NETs < 0.5 cm (micro-NETs) were uneventful. Ki67-based grading proved efficient for the prognostic stratification of type III NETs; however, grade 2 (G2) was not associated with tumor behavior in type I NETs. Although G3 NETs (2 type I and 9 type III) had a very poor prognosis, it was found that patient survival was longer with type III G3 NETs compared to pdNECs.

CONCLUSIONS

Given the marked, tumor type-related behavior differences, evaluation of gastric NEN prognostic parameters should be tailored to the type of neoplastic disease.

Clinical Presentation and Diagnosis of Neuroendocrine Tumors

Neuroendocrine tumors (NETs) are slow-growing neoplasms capable of storing and secreting different peptides and neuroamines. Some of these substances cause specific symptom complexes, whereas others are silent. They usually have episodic expression, and the diagnosis is often made at a late stage. Although considered rare, the incidence of NETs is increasing. For these reasons, a high index of suspicion is needed. In this article, the different clinical syndromes and the pathophysiology of each tumor as well as the new and emerging biochemical markers and imaging techniques that should be used to facilitate an early diagnosis, follow-up, and prognosis are reviewed.

Histologic changes in type A chronic atrophic gastritis indicating increased risk of neuroendocrine tumor development: the predictive role of dysplastic and severely hyperplastic enterochromaffin-like cell lesions

The role of putative preneoplastic enterochromaffin-like cell lesions, either hyperplastic or dysplastic, in the genesis of type 1 enterochromaffin-like cell neuroendocrine tumors associated with type A chronic atrophic gastritis, their actual neoplastic risk, and their precise histogenetic mechanism deserve further clarification by specific histopathologic studies coupled with patient follow-up. A total of 100 patients with severe type A chronic atrophic gastritis, enterochromaffin-like cell hyperplasia, and antral G-cell hyperplasia were endoscopically and histologically followed up for a median of 90.1 months (total of 9118 person-months). Preneoplastic enterochromaffin-like cell lesions and newly developed neuroendocrine tumors were investigated histologically and histochemically, in parallel with enterochromaffin-like cell lesions found in nontumor mucosa of another 32 well-characterized and previously reported type 1 neuroendocrine tumors. Both neuroendocrine and nonneuroendocrine mucosa changes were analyzed and statistically evaluated. During follow-up, 7 of 100 patients developed neuroendocrine tumors: 5 were in a group of 20 cases with previous enterochromaffin-like cell dysplasia and 2 were among 80 cases showing only enterochromaffin-like cell hyperplasia throughout the study (hazard ratio, 20.7; P < .001). The severity of enterochromaffin-like cell hyperplasia at first biopsy, with special reference to linear hyperplasia with 6 chains or more per linear millimeter, also increased the risk of neuroendocrine tumor development during follow-up (hazard ratio, 13.0; P < .001). Enterochromaffin-like cell microinvasive dysplastic lesions arising at the epithelial renewal zone level, in connection with immature proliferating mucous-neck cells, were found to be linked to early intramucosal neuroendocrine tumor histogenesis. Both enterochromaffin-like cell dysplasia and severe hyperplasia indicate increased risk of neuroendocrine tumor development in type A chronic atrophic gastritis with hypergastrinemia/G-cell hyperplasia.

Gastric neuroendocrine tumours

BACKGROUND

Gastric neuroendocrine tumours (NETs) are increasingly recognised, and management decisions may be difficult due to an incomplete understanding of aetiology, natural history and optimum therapy. This article presents a current understanding based on recent advances in epidemiology, classification, molecular profiling, and treatment.

METHODS

Relevant medical literature was identified from searches of PubMed and references cited in appropriate articles identified. Selection of articles was based on peer review, journal and relevance.

RESULTS

Gastric NETs may be divided into three clinical prognostic groups: type I is associated with autoimmune atrophic gastritis and hypergastrinaemia, type II is associated with Zollinger-Ellison syndrome, and type III lesions are gastrin-independent, have the greatest metastatic potential and poorest prognosis. There has been an increased frequency of gastric NETs reported. Management approaches have evolved in parallel with advances in endoscopic staging and surgery, as well as improved understanding of the biology and natural history of NETs.

CONCLUSIONS

Gastric NETs present a spectrum of activity from indolent tumours to metastatic malignancy. Treatment decisions for patients must be individualised and are best managed by a multidisciplinary team approach. The current evidence base is limited to small series and efforts to treat patients within clinical networks of expertise are warranted.

A review of stress-related mucosal disease

OBJECTIVE

To review and summarize the human and veterinary literature regarding stress-related mucosal disease (SRMD) pathogenesis, patient risk factors, and therapeutic options for prophylaxis and treatment.

ETIOLOGY

SRMD is a common sequela of critical illness in human patients. Development of SRMD results from splanchnic hypoperfusion, reperfusion injury, and exposure of the gastric mucosa to acid, pepsin, and bile acids following breakdown of the gastric mucosal defense system. Human patients with the highest risk of stress ulceration include those with respiratory failure necessitating mechanical ventilation greater than 48 h or coagulopathy. Currently, little is known about the incidence and pathophysiology of SRMD in critically ill veterinary patients.

DIAGNOSIS

A presumptive diagnosis can be made in high-risk patient populations following detection of occult or gross blood in nasogastric tube aspirates, hematemesis, or melena. Definitive diagnosis is achieved via esophagogastroduodenoscopy. Lesions are localized to the acid-producing portions of the stomach, the fundus, and body.

THERAPY

Therapy is aimed at optimization of tissue perfusion and oxygenation. Pharmacologic interventions are instituted to increase intraluminal pH and augment natural gastric defenses. Histamine(2)-receptor antagonists, proton pump inhibitors, and sucralfate are the mainstays of therapy. In people, clinically significant bleeding may necessitate additional interventions (eg, packed red blood cell transfusions, endoscopic, or surgical hemostasis).

PROGNOSIS

Mortality is increased in people with clinically significant bleeding compared to those patients who do not bleed. Institution of prophylaxis is recommended in high-risk patients. However, no consensus exists regarding initiation of prophylaxis, preference of frontline drug class, or indication for discontinuation of therapy. The prognosis of veterinary patients with SRMD remains unknown at this time.

Unusually aggressive type 1 gastric carcinoid: a case report with a review of the literature

Gastric carcinoids are rare tumors of the stomach. Gastric carcinoid type 1 is associated with chronic atrophic gastritis, and because of a low metastatic potential, is the most benign type. Death from metastatic disease has been reported in only three patients in a review including 724 cases. The present report refers to a 60-year-old man who was affected by type 2 diabetes mellitus and pernicious anemia and died from metastatic gastric carcinoid type 1. In 1998, a well-differentiated 1.2 cm gastric neuroendocrine tumor, immunoreactive for chromogranin A, with a Ki-67 index less than 2% and with infiltration to the submucosal layer was diagnosed and enucleated. In 2002, a new well-differentiated gastric endocrine tumor 6 mm in size with a Ki-67 of approximately 2% was detected, and endoscopic ultrasound confirmed it to be limited to the submucosal layer. The patient refused antrectomy and started long-acting somatostatin analog (lanreotide) in 2005 when the Ki-67 index was 7%, but he stopped the treatment after 4 months. In 2007, despite previous endoscopic stability, endoscopic ultrasound showed an infiltrating gastric lesion of 7 cm. At surgery, the disease appeared to be extended to the liver and to the peritoneum (well-differentiated endocrine carcinoma, Ki-67 40%) with both hepatic and massive peritoneal metastases. A regimen of somatostatin analog was soon restarted; however, the disease continued to spread, and the patient died 6 months later. Overall, despite their generally benign course, type 1 gastric carcinoids may have malignant potential, a finding that should be considered when planning the medical workup of these patients.

Histologic characterization and improved prognostic evaluation of 209 gastric neuroendocrine neoplasms

Gastric neuroendocrine neoplasms differ considerably in histology, clinicopathologic background, stage, and patient outcome, implying a wide spectrum of therapeutic options, hence the need for improved diagnostic and prognostic criteria to select appropriate therapy. Here, we tested the European NeuroEndocrine Tumor Society and the novel World Health Organization 2010 grade and stage classifications together with additional clinicopathologic and histologic parameters in a series of 209 gastric neuroendocrine neoplasms with a median follow-up of 89 months. Fifty-one grade 3 neuroendocrine carcinomas and 15 mixed endocrine-exocrine carcinomas of poor outcome were separated from 143 neuroendocrine tumors, including 132 G1 or G2 enterochromaffin-like (ECL) cell neoplasms and 11 G1 gastrin-cell, somatostatin-cell, or serotonin-cell tumors. Most G1 cases had excellent prognosis, even when metastatic, whereas G2 and G3 neoplasms had worse or very severe prognosis, respectively. The European NeuroEndocrine Tumor Society-World Health Organization 2010 proliferative grading system well correlated with patient survival. Structural histologic parameters were equally predictive and when combined with the European NeuroEndocrine Tumor Society-World Health Organization 2010 grading system in a "global grade" improved tumor prognostic stratification. The European NeuroEndocrine Tumor Society-World Health Organization 2010 staging system proved effective. Introduction of novel T (T(1a) and T(1b) or deep submucosal) and N categories (N(1), <3 nodes metastases; N(2), ≥3) allowed a simplified, equally informative 3-stage TNM system. Such improved diagnostic and prognostic criteria for gastric neuroendocrine neoplasms are proposed and discussed.

A clinical perspective on gastric neuroendocrine neoplasia

The incidence of gastric neuroendocrine tumors (NETs) has increased exponentially based on widespread use of endoscopy and a greater pathological awareness of the condition. A key concern is the potential association with hypergastrinemia induced by proton pump inhibitor administration. Previous confusion regarding diagnosis and therapy has been diminished by a series of international consensus statements defining the biology and management strategies for the disease. Overall, gastric NETs are categorized as well-differentiated or poorly differentiated neoplasms. Well-differentiated gastric NETs are enterochromaffin-like (ECL) cell tumors subclassified into three types based on their relationship to gastrin, a key regulator of ECL cell neoplastic transformation. The treatment of type 1 and type 2 tumors depends on the size and invasiveness of the tumor, whereas type 3 tumors and poorly differentiated neuroendocrine carcinomas warrant aggressive surgical resection. The disease-specific 5-year survival ranges from about 95% in type 1 gastric carcinoids to about 25% in poorly differentiated gastric NECs. Elucidation of the precise biology of a gastric NET is critical to diagnosis and delineation of a type-specific management strategy.

Nonantral gastric carcinoid tumours associated with hypergastrinaemia

Nonantral gastric carcinoid tumours in association with pronounced hypergastrinaemia are reported in 6 patients. It is suggested that the hypergastrinaemia, as a result of lack of a negative acid feedback inhibition in an achlorhydric stomach, promoted the tumour development, possibly initiated by action of carcinogenic nitrosamines, in the gastric juice.

Gastric polyps: classification and management

Gastric polyps can be broadly defined as luminal lesions projecting above the plane of the mucosal surface. They are relatively frequent in routine pathology practice, where the main goal is to rule out the possibility of malignancy. Various subtypes of gastric polyps are recognized and generally divided into nonneoplastic and neoplastic. We will review herein only a limited subset of gastric polyps representing the most common or, sometimes, challenging.

Endocrine tumours of the gastrointestinal tract-selected topics

This review provides an update on the pathogenesis and histopathological diagnosis of endocrine tumours of the gastrointestinal tract, concentrating on three different varieties whose careful assessment by pathologists is of particular clinical significance. These are the four types of enterochromaffin-like cell tumour of the gastric corpus, the periampullary somatostatin-containing D-cell tumour of the duodenum, and the frequently chromogranin A-negative L-cell tumour of the appendix and large intestine. In addition, the value of pathological factors in predicting the behaviour of gastrointestinal endocrine tumours and selecting therapy is discussed, and the crucial role of the pathologist in the multidisciplinary team management of these neoplasms is emphasized.

Consequences of long-term proton pump blockade: insights from studies of patients with gastrinomas

Proton pump inhibitors are being increasingly used and for longer periods of time, especially in patients with gastroesophageal reflux disease. Each of these trends has led to numerous studies and reviews of the potential risk-benefit ratio of the long-term use of proton pump inhibitors. Both long-term effects of hypergastrinaemia due to the profound acid suppression caused by proton pump inhibitors as well as the effects of hypo-/achlorhydria per se have been raised and studied. Potential areas of concern that have been raised in the long-term use of proton pump inhibitors, which could alter this risk-benefit ratio include: gastric carcinoid formation; the development of rebound acid hypersecretion when proton pump inhibitor treatment is stopped; the development of tolerance; increased oxyntic gastritis in H. pylori patients and the possibility of increasing the risk of gastric cancer; the possible stimulation of growth of non-gastric tumours due to hypergastrinaemia; and the possible effect of the hypo/achlorhydria on nutrient absorption, particularly iron and vitamin B12. Because few patients with idiopathic gastro-oesophageal reflux disease/peptic ulcer disease have been treated long-term (i.e., >10 years), there is little known to address the above areas of potential concern. Most patients with gastrinomas with Zollinger-Ellison syndrome have life-long hypergastrinaemia, require continuous proton pump inhibitors treatment and a number of studies report results of >5-10 years of tratment and follow-up. Therefore, an analysis of Zollinger-Ellison syndrome patients can provide important insights into some of the safety concerns raised above. In this paper, results from studies of Zollinger-Ellison syndrome patients and other recent studies dealing with the safety concerns above, are briefly reviewed.

Familial Multiple Endocrine Neoplasia

In 1903, Erdheim described the case of an acromegalic patient with a pituitary adenoma and three enlarged parathyroid glands. Fifty years later, Underdahl et al reported 8 patients with a syndrome of pituitary, parathyroid, and pancreatic islet adenomas. In 1954, Wermer found that the syndrome was transmitted as a dominant trait. In 1959, Hazard et al described medullary (solid) thyroid carcinoma (MTC), a tumor that later was found to be a component of two endocrine syndromes. The first of these described by Sipple in 1961 comprised pheochromocytoma, MTC, and parathyroid adenoma. The second, described by Williams et al in 1966, was the combination of mucosal neuromas, pheochromocytoma, and MTC. In 1968, Steiner et al introduced the term "multiple endocrine neoplasia" (MEN) to describe disorders featuring combinations of endocrine tumors; they designated the Wermer syndrome as MEN 1 and the Sipple syndrome as MEN 2. In 1974, Sizemore et al concluded that the MEN 2 category included two groups of patients with MTC and pheochromocytoma: one with parathyroid disease and a normal appearance (MEN 2A) and the other without parathyroid disease but with mucosal neuromas and mesodermal abnormalities (MEN 2B). Later, additional nonendocrine conditions (von Recklinghausen neurofibromatosis and von Hippel-Lindau disease) were found accompanying other more recently described familial MEN syndromes, indicating that these diseases are very complicated disorders.

Regression of type II gastric carcinoids in multiple endocrine neoplasia type 1 patients with Zollinger-Ellison syndrome after surgical excision of all gastrinomas

Enterochromaffin-like (ECL) tumors are documented in patients with hypergastrinemia secondary to chronic atrophic gastritis or with Zollinger-Ellison syndrome and multiple endocrine neoplasia type 1 (ZES-MEN-1). In patients with ECL tumors and atrophic gastritis, normogastrinemia after antrectomy has resulted in resolution, regression, or stabilization of ECL tumors. The natural history of ECL tumors associated with ZES-MEN-1 following normalization of gastrin levels after gastrinoma resection has not been previously reported. The purpose of this study was to determine the course of ECL tumors in patients with ZES-MEN-1 following normalization of serum gastrin levels after gastrinoma resection. Two patients with ZES-MEN-1 had biopsy-proven ECL tumors on endoscopic evaluation. They then underwent surgical exploration that included distal pancreatectomy, enucleation of pancreatic head tumors, duodenotomy with excision of submucosal tumors, and peripancreatic lymphadenectomy. Gastric ECL tumors larger than 1.0 cm were locally excised. Patients underwent long-term follow-up with biochemical and endoscopic surveillance. Normogastrinemia was achieved and sustained following gastrinoma resection in two patients with ZES-MEN-1. Periodic endoscopic surveillance over a 6-year period showed complete resolution of the ECL tumors. The development of ECL tumors associated with ZES-MEN-1 is multifactorial. Studies identified a genetic influence on tumor growth with loss of heterozygosity at the MEN-1 gene locus in ECL tumors. The resolution of ECL tumors in ZES-MEN-1 patients who are normogastrinemic indicates that an elevated gastrin level is a primary initiator for development of these tumors. Therefore both genetic defects and hypergastrinemia are causative agents. Normalization of serum gastrin levels is critical for the prevention of aggressive forms of ECL tumors.

A 50-year analysis of 562 gastric carcinoids: small tumor or larger problem?

OBJECTIVES

Interest in gastric carcinoid tumors has amplified considerably given the biological establishment of their relationship to gastrin and advances in the elucidation of the pathobiology of such lesions. The recognized propensity of acid-suppressing agents such as the proton pump inhibitor class of drugs to increase plasma gastrin levels has been proposed as a causal relationship in the apparent increase in the identification of such lesions although the increased prevalence of endoscopy and the enhanced awareness of pathologists have also been considered as contributory factors. We sought to examine if there has been an increase in gastric carcinoid incidence time correlative with these parameters.

METHODS

Carcinoid tumor cases from the End Results Group (1950-1969) and the Third National Cancer Survey (TNCS) (1969-1971) databases were combined with the most recent release of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) registry (1973-1999); these three datasets revealed 13715 carcinoid cases, of which 562 were gastric in origin. Age-adjusted analyses as well as population-based gender and race correction ratios were completed in conjunction with United States decennial census data. To allow a finer granularity in incidence trends, the SEER database was divided into early (1973-1991) and late (1991-1999) subsets. RESULTS Since 1950, the percentage of gastric carcinoids among all gastric malignancies has increased from 0.3% to 1.77%. Since 1969, the proportion of gastric carcinoids among all enteric carcinoid lesions has increased from 2.4% to 8.7%. Age-adjusted incidence rates among male, female, black, and white population subsets have all increased since the TNCS time period, with the greatest increase (800%) noted in white females. The male:female ratio has fallen from 0.90 to 0.54. The occurrence of synchronous or metachronous noncarcinoid tumors with gastric carcinoid tumors has decreased by 26% during the course of SEER data collection. The 5-yr survival rate for gastric carcinoids overall has risen from 51% to 63% during the same time period.

CONCLUSIONS

Gastric carcinoids have increased in incidence over the last 50 yr. Differential increases in predominance across gender and race subdivisions may reflect genetic-based propensities (or protection) for gastric carcinoid tumors among certain ethnic populations. Increased endoscopic surveillance and associated sophisticated pathological evaluation of gastric biopsies undoubtedly are responsible for some of the observed increase in the incidence of gastric carcinoid tumors. These data allow no specific role to be assigned to the effects of acid-suppressive medications. Nevertheless the role of such agents cannot be discounted at this time since the time frame of the increased incidence is somewhat comparable to the introduction of these agents as is the known biological effect of gastrin on ECL cell proliferation.

Safety and efficacy of long term esomeprazole therapy in patients with healed erosive oesophagitis

OBJECTIVE

To evaluate the safety and tolerability of long term treatment with esomeprazole in patients with healed erosive oesophagitis, and to describe its efficacy in the maintenance of healing.

DESIGN AND SETTING

US multicentre, noncomparative, nonblind study.

PATIENTS AND PARTICIPANTS

807 patients with endoscopically confirmed healed erosive oesophagitis.

METHODS

Patients received esomeprazole 40 mg once daily for up to 12 months. Adverse events and clinical laboratory tests were assessed over the study period. Endoscopy was performed at the final visit of the antecedent healing trials and at months 6 and 12 of the current safety trial; gastric biopsies were obtained at the initial visit of the healing trials and at the end of the safety trial.

RESULTS

80.9% of patients completed 6 months of treatment; 76.6% completed 12 months of treatment. There were no serious drug-related adverse events. Diarrhoea, abdominal pain, flatulence, and headache were the only treatment-related adverse events reported by >3% of patients. Mean changes in laboratory measures were generally small and not clinically meaningful. Plasma gastrin levels increased, as expected, and reached a plateau after 3 months. No changes in gastric histological scores were noted in the majority of patients. Evaluation of gastric biopsies revealed an overall decline in chronic inflammation and atrophy. Intestinal metaplasia findings remained essentially unchanged. Life table estimates of maintenance of healing were 93.7% [95% confidence interval (CI) 92.0 to 95.5%] at 6 months and 89.4% (95% CI 87.0 to 91.7%) at 12 months.

CONCLUSIONS

Daily treatment with esomeprazole 40 mg for up to 1 year in patients with healed erosive oesophagitis was generally well tolerated and effective. No safety concerns arose.

Gastric endocrine cells: types, function and growth

The history of gastric endocrine cells identification and functional characterization is briefly outlined. An up to date classification of such cells is given. Present status of histopathological, histochemical, ultrastructural and molecular investigations on gastric endocrine hyperplasia and neoplasia is summarized and briefly discussed.

A rare case of multiple carcinoids and endocrine cell micronests in a patient with chronic duodenitis

BACKGROUND

To the authors' knowledge, multiple carcinoid tumors of the duodenum have not been reported previously. However, multiple carcinoids in the stomach, ileum, and rectum, which were accompanied by the proliferation of endocrine cells, have been reported in the published literature.

METHODS

A patient with multiple carcinoids including argyrophilic cell hyperplasia of the duodenum and hypergastrinemia underwent surgery. The resected stomach and duodenum were analyzed histopathologically.

RESULTS

There were 11 carcinoid lesions, each of which was accompanied by peripheral endocrine cell micronests (ECMs). Increasing gastrin positive cells in the antral region and chronic duodenitis in the duodenal bulb also were observed. The peripheral ECMs usually were adjacent to proliferating argyrophilic cells in the Brunner gland ducts or the crypts of Lieberkühn, which showed focal pyloric gland metaplasia.

CONCLUSIONS

In the case presented in the current study, the development of the multiple carcinoid lesions may be strongly related to the presence of multifocal pyloric gland metaplasia, as well as to the trophic action of gastrin, which is present at high levels in the setting of chronic duodenitis.

Review article: potential gastrointestinal effects of long-term acid suppression with proton pump inhibitors

This review examines the evidence for the development of adverse effects due to prolonged gastric acid suppression with proton pump inhibitors. Potential areas of concern regarding long-term proton pump inhibitor use have included: carcinoid formation; development of gastric adenocarcinoma (especially in patients with Helicobacter pylori infection); bacterial overgrowth; enteric infections; and malabsorption of fat, minerals, and vitamins. Prolonged proton pump inhibitor use may lead to enterochromaffin-like cell hyperplasia, but has not been demonstrated to increase the risk of carcinoid formation. Long-term proton pump inhibitor treatment has not been documented to hasten the development or the progression of atrophic gastritis to intestinal metaplasia and gastric cancer, although long-term studies are required to allow definitive conclusions. At present, we do not recommend that patients be tested routinely for H. pylori infection when using proton pump inhibitors for prolonged periods. Gastric bacterial overgrowth does increase with acid suppression, but important clinical sequelae, such a higher rate of gastric adenocarcinoma, have not been seen. The risk of enteric infection may increase with acid suppression, although this does not seem to be a common clinical problem with prolonged proton pump inhibitor use. The absorption of fats and minerals does not appear to be significantly impaired with chronic acid suppression. However, vitamin B12 concentration may be decreased when gastric acid is markedly suppressed for prolonged periods (e.g. Zolllinger-Ellison syndrome), and vitamin B12 levels should probably be assessed in patients taking high-dose proton pump inhibitors for many years. Thus, current evidence suggests that prolonged gastric acid suppression with proton pump inhibitors rarely, if ever, produces adverse events. Nevertheless, continued follow-up of patients taking proton pump inhibitors for extended periods will provide greater experience regarding the potential gastrointestinal adverse effects of long-term acid suppression.

Morphological, molecular, and prognostic aspects of gastric endocrine tumors

This paper aims at describing the neuroendocrine cell growths of the gastric mucosa and their pathogenesis. In the corpus-fundus mucosa, gastric neuroendocrine nontumor growths are mostly represented by hyperplastic and, more rarely, dysplastic enterochromaffin-like (ECL) cell changes, while hyperplasia of gastrin-producing (G) cells and, rarely, of somatostatin-producing (D) cells are reported in the antral mucosa. The large majority of gastric neuroendocrine tumors is made by benign, gastrin-dependent, well-differentiated ECL cell growths arising in a background of chronic atrophic gastritis (type I) or, more rarely, associated with type I multiple endocrine neoplasia (MEN I) and Zollinger-Ellison (ZE) syndromes (type II). Rare, aggressive, frequently metastatic, well-differentiated gastric neuroendocrine tumors are gastrin-independent and arise as sporadic lesions in the absence of specific gastric pathology (type III). Poorly differentiated neuroendocrine carcinomas (PDEC) are rare, highly aggressive carcinomas. A central role for gastrin is postulated in the pathogenesis of well-differentiated type I and II ECL cell tumors with different possible genetic mechanisms. A more complex genetic background, independent of gastrin and possibly implicating altered function or mutation of p53 and other genes is highly suspected for the development of aggressive type III ECL cell carcinomas and PDECs.

Morphological changes of the human gastric mucosa under long-term proton pump inhibitor therapy and their clinical relevance

Proton pump inhibitors are potent drugs for the treatment of acid-related diseases. The moderate hypergastrinaemia observed during therapy is a physiological response to low intragastric pH and the increase is limited to the first months of therapy with no further changes thereafter. Reports on endocrine cell changes in the antral mucosa under chronic PPI therapy are controversial and lack clinical relevance. In contrast, in the oxyntic mucosa hyperplastic argyrophil cell changes have been reported, dependent on the degree and duration of hypergastrinaemia, the severity of oxyntic mucosal gastritis, especially atrophy, and the presence of H. pylori infection. Current data do not support a progression from hyperplastic to dysplastic argyrophil cell lesions in humans in the absence of additional genetic factors. Data on the progression of oxyntic gastritis under chronic PPI treatment in comparison to untreated controls could not be confirmed in more recent studies including a well-matched control population. The main factor for gastritis progression is the presence of Helicobacter pylori infection. The bacterium not only causes a chronic inflammation of the gastric mucosa, resulting in atrophy and intestinal metaplasia, but also influences endocrine cell populations involved in the regulation of gastric acid secretion. The clinical benefit of H. pylori eradication in reflux esophagitis patients is still a matter of debate. The complex relations in humans between hypergastrinaemia, (oxyntic) gastritis and atrophy, H. pylori infection, argyrophil cell hyperplasia, and the effects of long-term PPI treatment of acid-related diseases do not allow a quantification of the contribution of each single factor for the observed changes.

Clinical and histopathological tumour progression in ECL cell carcinoids ("ECLomas")

AIMS

The aims of this study were to illustrate the malignant potential of gastric enterochromaffin-like (ECL) cell carcinoids (ECLomas) associated with hypergastrinemia, and the gradual neoplastic progression of such tumours. In addition, we examined whether the tyramide signal amplification (TSA) technique could visualize immunohistochemical (IHC) neuroendocrine (NE) features in the dedifferentiated neoplastic ECL cells which were not detected by conventional methods.

METHODS

Conventional histopathological and IHC methods for visualizing ECL cells and cell proliferation were used in addition to the TSA technique.

OBSERVATIONS

Our patient was followed for 5 years. During that period, her ECLoma displayed all the signs of classical tumour progression, ultimately with the appearance of metastases in the regional lymph nodes, the liver and the skin. The neoplastic ECL cells became progressively dedifferentiated with an increasing number of Ki-67 immunoreactive (IR) cell nuclei. In addition, there was a substantial decrease in argyrophil and IR NE cells that could be visualized by conventional methods. By applying the TSA technique, however, the number of IR tumour cells increased considerably.

CONCLUSIONS

ECLomas secondary to hypergastrinemia should be closely followed for signs of clinical and histopathological tumour progression. Such ECLomas deserve early, active, radical surgical treatment. The TSA technique is a valuable tool for visualizing the characteristic IHC features in dedifferentiated NE cells.

ECL cell tumor and poorly differentiated endocrine carcinoma of the stomach: prognostic evaluation by pathological analysis

BACKGROUND & AIMS

Gastric endocrine tumors show a wide spectrum of clinical behavior, and prognostic assessement of individual tumors is difficult. The aims of this work were to identify predictors of tumor malignancy and patient outcome and to provide a rationale for treatment guidelines.

METHODS

Gastric endocrine tumors (86 enterochromaffin-like cell carcinoids and 16 poorly differentiated carcinomas) were investigated for 15 clinicopathologic variables and for expression of Ki67, P53, and BCL-2 proteins. Data were analyzed by univariate and multivariate statistics for evidence of tumor malignancy and patient survival.

RESULTS

Histological grades 2 and 3, size >/=3 cm, 9 or more mitoses, or >/=300 Ki67-positive cells per 10 high-power fields identified 26 of 33 (79%) malignant (metastatic or deeply invasive) tumors, and size <1 cm and/or growth restricted to the mucosa characterized 46 of 69 (67%) tumors with benign behavior during a median follow-up of 39 months. Malignancy-predictive models were developed using angioinvasion, size, clinicopathologic type, mitotic index, and Ki67 index. The same variables, in addition to deep gastric wall invasion and histological grade, predicted patient outcome.

CONCLUSIONS

Criteria for the assessment of malignancy risk and patient outcome were developed for the different tumors, providing a basis for treatment guidelines.

Serum gastrin and chromogranin A during medium- and long-term acid suppressive therapy: a case-control study

BACKGROUND

Serum chromogranin A (CgA) is regarded as a reliable marker of neuroendocrine proliferation. We previously described increased serum CgA levels during short-term profound gastric acid inhibition.

AIM

To investigate serum gastrin and CgA levels in dyspeptic patients during continuous medium- (6 weeks to 1 year), or long-term (1-8 years) gastric acid suppressive therapy.

PATIENTS AND METHODS

114 consecutive dyspeptic patients referred for upper gastrointestinal endoscopy were enrolled in a cross-sectional, case-control study [62 patients on continuous antisecretory therapy, either with proton pump inhibitors (n = 47) or H2-receptor antagonists (H2RA) (n = 15) for gastro-oesophageal reflux disease with or without Barrett's oesophagus or functional dyspepsia, and 52 age- and sex-matched patients without medical acid inhibition and with normal endoscopic findings (control group)]. Omeprazole doses ranged from 20 mg to 80 mg daily and ranitidine from 150 mg to 450 mg daily. Fasting serum CgA and serum gastrin levels were measured by radioimmunoassay (reference values: serum CgA < 4.0 nmol/L; serum gastrin < 85 ng/L).

RESULTS

Fasting serum CgA levels positively correlated with serum gastrin in the entire study population (r = 0. 55, P = 0.0001). Median serum CgA values were higher in patients treated with a proton pump inhibitor than H2RA [2.8 (2.0-5.9) nmol/L vs. 2 (1.9-2.3) nmol/L, P < 0.002] and controls [2.8 (2.0-5.9) nmol/L vs. 1.8 (1.5-2.2) nmol/L, P < 0.0001) and did not differ between patients treated with H2RA or controls. Serum gastrin and CgA levels in patients on proton pump inhibitor therapy positively correlated with the degree and duration of acid inhibition. Patients on long-term proton pump inhibitor therapy had significantly higher fasting serum gastrin and CgA than those on medium-term proton pump inhibitor therapy [127 (73-217) ng/L vs. 49 (29-78) ng/L, P < 0.0001 and 4.8 (2.8-8) ng/L vs. 2.1 (1.9-2.6) ng/L, P < 0.001]. No such relation was found in patients on medium- vs. long-term H2RA. Overall, patients with positive Helicobacter pylori serology had higher serum gastrin and CgA levels than those with negative H. pylori serology [51 (27-119) ng/L vs. 27 (14-79) ng/L, P = 0.01, 2.4 (1.9-3.4) nmol/L vs. 2.0 (1.7-2.5) nmol/L, P = 0.05].

CONCLUSIONS

During long-term continuous proton pump inhibitor treatment, serum gastrin and CgA levels are significantly elevated compared to H2RA treatment and nontreated dyspeptic controls. H. pylori infection seems to affect gastric ECL cell secretory function. Increased serum CgA values during long-term profound gastric acid inhibition could reflect either gastric enterochromaffin-like cell hyperfunction or proliferative changes.

Gastrin induces heparin-binding epidermal growth factor-like growth factor in rat gastric epithelial cells transfected with gastrin receptor

BACKGROUND & AIMS

Parietal cells express heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF). However, it is unknown whether HB-EGF mediates the trophic action of gastrin. The purpose of this study was to determine whether gastrin modulates the expression of HB-EGF, which mediates the proliferative effects of gastrin on gastric epithelial cells.

METHODS

RGM1 cells, a rat gastric epithelial cell line, were transfected with a human gastrin receptor complementary DNA. Gastrin induction of messenger RNAs (mRNAs) for EGF-related polypeptides was assayed by Northern blotting. Processing of cell surface-associated proHB-EGF and secretion of HB-EGF were determined by flow cytometry and Western blotting, respectively. Tyrosine phosphorylation of the EGF receptor was assayed by immunoprecipitation and Western blotting with an antiphosphotyrosine antibody. Cell growth was evaluated by [3H]thymidine incorporation.

RESULTS

Gastrin induced expression of HB-EGF mRNA, processing of proHB-EGF, release of HB-EGF into the medium, and tyrosine phosphorylation of the EGF receptor. The growth-stimulatory effects of gastrin were partly inhibited by anti-rat HB-EGF serum and completely blocked by AG1478, an EGF receptor-specific tyrphostin.

CONCLUSIONS

The findings suggest that HB-EGF at least partially mediates the proliferative effects of gastrin on gastric epithelial cells.

Reversal of fundic atrophy after eradication of Helicobacter pylori

OBJECTIVES

We sought to evaluate the effect of Helicobacter pylori eradication in patients with fundic atrophic gastritis.

METHODS

Acid secretion, gastric emptying, and histology were evaluated in 20 patients with fundic atrophic gastritis and H. pylori infection. After investigation, 10 patients (Group 1) received an eradicating treatment and 10 (Group 2) did not receive any treatment. One year later, the baseline investigations were repeated. Subsequently, patients in Group 2 received the same treatment given to patients in Group 1 and were reevaluated 12 months later. A further follow-up was performed in both groups 36 months after the treatment.

RESULTS

At 1-yr follow-up, all the patients in Group 1 were H. pylori negative whereas all the patients in Group 2 were still infected. In Group 1, there was a significant improvement of both fundic atrophy and acid secretion, compared with baseline (p < 0.01). In Group 2, no substantial modification of either histological or functional parameters was observed at the first follow-up; conversely, a significant (p < 0.01) improvement of fundic atrophy and acid secretion was detected in these patients 12 months after eradication of the bacterium. Histological pattern remained unchanged at 36 months of follow-up in both groups. Gastric emptying remained, on the average, unaffected by the treatment; however, three patients with delayed gastric emptying at entry had normal gastric emptying after eradication of H. pylori.

CONCLUSIONS

Our data suggest that mucosal atrophy can be reduced or even reversed by the eradication of H. pylori, and this is associated with a recovery of gastric function.

Gastric carcinoid expresses the gastrin autocrine pathway

BACKGROUND

In gastric adenocarcinoma the gastrin autocrine-paracrine pathway is activated. As enterochromaffin-like (ECL) cells originate from the same stem as epithelial cells, the aim of this study was to determine if the gastrin autocrine pathway is present in gastric carcinoid.

METHODS

Samples from ten patients with gastric carcinoid were assessed by immunocytochemistry using primary antibodies directed against gastrin precursors and the gastrin/cholecystokinin B receptor and detected using the avidin-biotin immunoperoxidase system.

RESULTS

A high level of expression of precursor and mature gastrin peptides, together with the gastrin receptor, was seen in all carcinoids screened.

CONCLUSION

In common with the glandular epithelium of the stomach the gastrin gene is activated during the neoplastic process in ECL cells. This finding may explain why some carcinoids do not regress after surgical procedures that lower serum gastrin. Antigastrin agents may be a useful treatment for carcinoid either in their own right or as an adjunct to surgery.

Clinical symptoms, hormone profiles, treatment, and prognosis in patients with gastric carcinoids

BACKGROUND

Type 1 gastric carcinoids are associated with hypergastrinaemia and chronic atrophic gastritis, type 2 occur in patients with multiple endocrine neoplasia type 1 combined with Zollinger-Ellison syndrome, and type 3 lack any relation to hypergastrinaemia. Type 1 tumours are usually benign whereas type 3 are highly malignant.

AIMS

To identify possible tumour markers in patients with gastric carcinoids.

PATIENTS/METHOD

Nine patients with type 1, one with type 2, and five with type 3 were evaluated with regard to symptoms, hormone profile, and prognosis.

RESULTS

Plasma chromogranin A was increased in all patients but was higher (p < 0.01) in those with type 3 than those with type 1 carcinoids. All patients with type 3 carcinoids died from metastatic disease, but none of the type 1 patients died as a result of their tumours. One type 1 patient with a solitary liver metastasis received interferon alpha and octreotide treatment. Nine months later, the metastasis was no longer detectable. She is still alive eight years after diagnosis, without recurrent disease. This represents the only reported case of foregut carcinoid with an unresectable liver metastasis that seems to be have been cured by biotherapy.

CONCLUSIONS

Plasma chromogranin A appears to be a valuable tumour marker for all types of gastric carcinoid. Combination therapy with interferon alpha and octreotide may be beneficial in patients with metastasising type 1 gastric carcinoids.

Comparison of the signal transduction pathways activated by gastrin in enterochromaffin-like and parietal cells

BACKGROUND & AIMS

Gastrin stimulates acid secretion from parietal cells and histamine release from enterochromaffin-like (ECL) cells through identical gastrin receptors. However, gastrin has been shown to have a trophic effect only on ECL cells. The aim of this study was to compare gastrin-induced signal transduction pathways in the ECL and parietal cells of Mastomys natalensis, an African rodent.

METHODS

Both ECL and parietal cells were isolated from the gastric mucosa of M. natalensis, and intracellular signal transduction events in response to gastrin were investigated.

RESULTS

Gastrin elicited histamine release from ECL cells and acid secretion from parietal cells in association with enhanced inositol phospholipid turnover. Although gastrin increased [3H]thymidine incorporation into ECL cells, it had no effect on parietal cells. Moreover, tyrosine phosphorylation and activation of mitogen-activated protein (MAP) kinase as well as c-fos and c-jun gene expression were augmented only in ECL cells. In addition, gastrin increased the formation of guanosine triphosphate-Ras with a simultaneous decrease in guanosine diphosphate-Ras levels in ECL but not in parietal cells.

CONCLUSIONS

Although gastrin receptors are present in both ECL and parietal cells, they activate the Ras-MAP kinase pathway only in ECL cells.

Malignant Thymic Carcinoid in Multiple Endocrine Neoplasia Type I Syndrome: Case Report and Literature Review

OBJECTIVE

To describe a case of thymic carcinoid tumor in association with multiple endocrine neoplasia type I (MEN I) and discuss the various manifestations of this syndrome.

METHODS

We present the clinical and laboratory data, including histopathologic and immunocytochemical findings, for our current patient and also review the literature on MEN I syndromes.

RESULTS

In a 46-year-old Caucasian man with no family history of multiple endocrine neoplasia, numerous MEN I lesions developed over time. The patient had gastrinoma of the duodenum, Zollinger-Ellison syndrome, hyperparathyroidism, a nonfunctioning adrenal mass, and foregut carcinoid tumors, including gastric and malignant thymic carcinoids. He sequentially underwent partial gastrectomy in conjunction with Billroth II anastomosis, a four-gland parathyroidectomy, and palliative radiotherapy for malignant carcinoid tumor, as well as endoscopic excision of accessible tumors.

CONCLUSION

The involvement in MEN I can be clinically complex. Early detection of MEN I lesions will facilitate timely implementation of treatment and help minimize complications.

The risk of gastric carcinoma and carcinoid tumours in patients with pernicious anaemia. A prospective follow-up study

BACKGROUND

This endoscopic follow-up study was undertaken to evaluate the risk of gastric cancer (GC) and carcinoids in patients with pernicious anaemia (PA) and to analyse whether early detection of GC could be provided by regular endoscopic follow-up.

METHODS

Screening gastroscopy was performed in 71 patients with pernicious anaemia, and thereafter they were followed up with gastroscopies at 3-year intervals for a mean time of 5.8 years. Standardized incidence ratios (SIR) were calculated, the expected number being based on incidence rates in the whole Finnish population.

RESULTS

Two GCs were found during the follow-up period; one of these patients was asymptomatic and the other had abdominal symptoms. The SIR was 5.0 (95% confidence interval, 0.6-18). Eight carcinoids were detected, and all but one were removed endoscopically, and no metastases were found. The patients who had carcinoid tumours were younger at the diagnosis of PA than those who did not develop carcinoids (mean, 40 versus 55 years). Additionally, the patients with carcinoids had longer duration of PA (mean, 11 versus 5 years).

CONCLUSIONS

During the follow-up period the risk of GC was increased. The risk of gastric carcinoids seems to be very high in patients with pernicious anaemia when compared with a normal population, but they are mostly relatively benign tumours. Regular routine gastroscopic follow-up is not indicated in patients with pernicious anaemia.

(3R)-N-(1-(tert-butylcarbonylmethyl)-2,3-dihydro-2-oxo-5-(2-pyridyl)-1H-1,4-benzodiazepin-3-yl)-N'-(3-(methylamino)phenyl)urea (YF476): a potent and orally active gastrin/CCK-B antagonist

A number of new 1,4-benzodiazepin-2-one-based gastrin/CCK-B receptor antagonists related to the archetypal analogue L-365,260, and more closely to the recently reported compound YM022, have been synthesized and evaluated for biological activity. The compounds were screened for their ability to inhibit the binding of [125I]CCK-8 to gastrin/CCK-B receptors prepared from rat brains and that of [3H]L-364,718 to CCK-A receptors from rat pancreas, and were shown to be potent and selective ligands for the gastrin/CCK-B receptor. Functional studies in vivo demonstrated the compounds to be antagonists of the receptor as evidenced by their ability to inhibit pentagastrin-induced gastric acid secretion in anesthetized rats. More extensive evaluation in vivo included determination of ED50 values in the rat acid secretion model for selected compounds and an examination of the effect of these compounds on pentagastrin-induced gastric acid secretion in Heidenhain pouch dogs following oral and intravenous administration. Two compounds, i.e. (3R)-N-[1-[(tert-butylcarbonyl)methyl]-2,3-dihydro-2-oxo-5-(2-pyri dyl) -1H-1,4-benzodiazepin-3-yl]-N'-[3-(methylamino)phenyl]urea, 15c (YF476), and (3R)-N-[1-[(tert-Butylcarbonyl)methyl]-2,3-dihydro-2-oxo-5- (2-pyridyl)-1H-1,4-benzodiazepin-3-yl]-N'-[3-(dimethylamino)phenyl ]urea hydrochloride, 15d, showed potent dose-dependent effects in both models with the former showing excellent oral bioavailability and an ED50 of 21nmol/kg po in dogs. 15c is currently under clinical investigation for the treatment of gastro-oesophagal reflux disease (GORD).

Gastrointestinal endocrine tumours. Gastrinoma

Since the description of the Zollinger-Ellison syndrome in two patients in 1955, there have been significant advances in the understanding of its pathogenesis, natural history, relationship to multiple endocrine neoplasia type 1, diagnosis, methods of tumour localization and management. The main focus in treatment is now shifting from management of the gastric acid hypersecretory state which can now be controlled medically in almost every patient, to the management of the gastrinoma. Recent studies are beginning to provide insights into the natural history of gastrinomas, factors that are associated with invasiveness in some gastrinomas, defining the role of surgery in managing patients with different disease extents, or with MEN 1 and being able to provide insights into molecular abnormalities that may be important in their pathogenesis. In this article each of these advances is briefly reviewed with emphasis primarily on recent advances.

The effect of vagotomy on enterochromaffin-like cells in Mastomys natalensis

The effect of vagotomy on the development of ECL cell tumours was analyzed during drug-induced hypergastrinemia in Mastomys natalensis, a rodent prone to develop ECL cell tumours. Untreated animals were compared with animals receiving the histamine2-receptor blocker loxtidine (LOX) and with animals subjected to unilateral subdiaphragmatic vagotomy prior to loxtidine treatment (VAG+LOX). Loxtidine (2g/l) was administered in drinking water for 48 weeks to allow multiple ECL cell carcinoids to develop. Plasma gastrin levels were increased in LOX animals (94 +/- 31 pmol/l) and in VAG+LOX animals (181 +/- 59 pmol/l) compared to controls (45 +/- 4 pmol/l). Corpus weight and oxyntic mucosal thickness was almost doubled in all loxtidine-treated animals and the density of mucosal endocrine cells was increased by 65% in the LOX group and by 135% in VAG+LOX animals. No significant differences in mucosal thickness and endocrine cell density were seen when denervated and intact parts of the stomach were compared. In the VAG+LOX animals endocrine cell neoplasia was seen in 60% and dysplasia in 40% of animals compared to 40% neoplasia, 45% dysplasia and 15% hyperplasia in LOX animals. The frequency of neoplastic and dysplastic lesions did not differ between denervated and intact parts of the stomach. Untreated animals showed no neoplastic or dysplastic lesions. It is concluded that unilateral vagotomy has no protective effect on the development of ECL-cell tumours in Mastomys during hypergastrinemia, as opposed to previous studies in the rat.

The histopathological spectrum of type A gastritis

It has been recently shown that type A gastritis can be histologically diagnosed in the preatrophic stage. In order to evaluate whether parietal cell atrophy in AG might correlate with other histopathological findings in the antral and body mucosa, we retrospectively investigated 171 consecutive cases of histologically diagnosed preatrophic (active) or atrophic type A gastritis (H&E, Warthin-Starry). The prevalences of intestinal metaplasia (75% vs 44.4%) and micronodular hyperplasia (86.1% vs 52.4%) of endocrine cells in the oxyntic mucosa were significantly higher of parietal cell atrophy was present (p < 0.001 and p < 0.0001, respectively), whereas the prevalence of nodular lymphoid aggregates (77.8% vs 48.1%) and of Helicobacter pylori (14.3% vs 1.9%) in the oxyntic mucosa was significantly higher if parietal cell atrophy could not be detected (p < 0.001 and p < 0.01, respectively). In the antral mucosa, altered patterns of the inflammatory reaction could be demonstrated independent of the parietal cell mass possibly caused by impaired gastric acid production. Our data support the notion that the development of parietal cell atrophy in type A gastritis represents a stepwise process including initial pseudohypertrophy of these cells.

Endocrine tumors of the gastrointestinal tract

Endocrine tumors of the gastrointestinal tract produce a variety of secretory products that cause unique clinical syndromes. Diagnosis, which is often delayed, requires a strong index of suspicion and must be confirmed by biochemical tests. Precisely where these tumors originate remains a topic of controversy. However, several growth factors that may be involved in tumor development have been identified, and genetic abnormalities in patients with multiple endocrine neoplasia have been described. New pre- and intraoperative localization techniques have greatly increased the ability to identify and resect these tumors. The long-acting somatostatin analogue octreotide is frequently useful as a tracer to localize tumors and as symptomatic therapy for limiting release of secretory products produced by the tumors. In some instances it may also have direct anti-tumor activity.

Inhibition of gastrin-stimulated enterochromaffin-like cell proliferation and mucosal histamine production in the rat stomach by the somatostatin analogue octreotide

The effect of octreotide, a potent and long-acting analogue of somatostatin, on gastrin-stimulated proliferation and function of enterochromaffin-like (ECL) cells were examined in rats. Animals were divided into four groups and each group was continuously infused with saline, octreotide alone (40 micrograms/kg per day), gastrin alone (60 nmol/kg per day), or octreotide (40 micrograms/kg per day) plus gastrin (60 nmol/kg per day) respectively for 9 days via osmotic minipumps. Gastrin induced the increase of the bromodeoxyuridine labeling index and density of oxyntic mucosal ECL cells as well as oxyntic mucosal histidine decarboxylase activity. Octreotide completely abolished the gastrin-induced increases in the labeling index and density of ECL cells and oxyntic mucosal histidine decarboxylase activity. These results indicate that octreotide inhibits gastrin-stimulated proliferation of ECL cells and histamine production by these cells.

Endocrine tumours of the stomach

This review illustrates the current classification of gastric endocrine tumors: a) carcinoid tumors (associated with chromic atrophic gastritis; with Zollinger-Ellison syndrome and multiple endocrine neoplasia type I; sporadic) and b) neuroendocrine carcinomas. The pathogenetic characteristics and clinical implications that justify this classification are discussed.

Are enterochromaffinlike cell tumours reversible? An experimental study on gastric carcinoids induced in Mastomys by histamine2-receptor blockade

A rapid induction of enterochromaffinlike (ECL) cell tumours has been shown in Praomys (Mastomys) natalensis subjected to histamine2-receptor blockade. In the present study the reversibility of ECL cell proliferation induced by acid inhibition was investigated. Short-term treatment (8 weeks) with the histamine2-receptor antagonist loxtidine caused a moderate hypergastrinemia, accompanied by a minor increase in histamine contents and a 2-fold increased volume density of the endocrine cells in gastric oxyntic mucosa. Eight weeks after withdrawal of treatment the volume density of endocrine cells was normalised as were the tissue levels of histamine, indicating a total reversibility of ECL cell hyperplasia. Long-term treatment (24 weeks) caused severe changes in the endocrine cell population of the oxyntic mucosa with neoplasia (5/21), dysplasia (11/21) and nodular hyperplasia (5/21). The endocrine cell density increased twofold and tissue histamine levels fourfold. 24 weeks after cessation of treatment, the endocrine cell density had decreased to 136% of controls, while histamine concentrations were normalised. The frequency of invasive carcinoids after recovery (4/23) differed only slightly from that seen after treatment for 24 weeks (5/21). Dysplastic lesions were only seen in 1/23 and hyperplastic lesions were of less severe type after recovery. The results demonstrate that ECL cell hyperplasia and dysplasia, induced by acid inhibition, are reversible after cessation of treatment. However, ECL cell tumours did not disappear, within the given observation period. One may therefore speculate that ECL cell proliferation is no longer reversible once the neoplastic (transformed) phenotype has developed.