Resistance to osimertinib in advanced EGFR-mutated NSCLC: a prospective study of molecular genotyping on tissue and liquid biopsies

BACKGROUND

Resistance to osimertinib in advanced EGFR-mutated non-small cell lung cancer (NSCLC) constitutes a significant challenge for clinicians either in terms of molecular diagnosis and subsequent therapeutic implications.

METHODS

This is a prospective single-centre study with the primary objective of characterising resistance mechanisms to osimertinib in advanced EGFR-mutated NSCLC patients treated both in first- and in second-line. Next-Generation Sequencing analysis was conducted on paired tissue biopsies and plasma samples. A concordance analysis between tissue and plasma was performed.

RESULTS

Sixty-five advanced EGFR-mutated NSCLC patients treated with osimertinib in first- (n = 56) or in second-line (n = 9) were included. We managed to perform tissue and liquid biopsies in 65.5% and 89.7% of patients who experienced osimertinib progression, respectively. Acquired resistance mechanisms were identified in 80% of 25 patients with post-progression samples, with MET amplification (n = 8), EGFR C797S (n = 3), and SCLC transformation (n = 2) the most frequently identified. The mean concordance rates between tissue and plasma for the EGFR activating mutation and for the molecular resistance mechanisms were 87.5% and 22.7%, respectively.

CONCLUSIONS

Resistance to osimertinib demonstrated to be highly heterogeneous, with MET amplification the main mechanism. Plasma genotyping is a relevant complementary tool which might integrate tissue analysis for the study of resistance mechanisms.

YES1 and MYC amplifications as synergistic resistance mechanisms to different generation ALK-TKIs in advanced NSCLC: brief report of clinical and preclinical proofs

Introduction

ALK tyrosine kinase inhibitors (TKIs) are the standard treatment for advanced ALK-positive NSCLC. Nevertheless, drug resistance inevitably occurs. Here, we report a case of a patient with metastatic ALK-positive lung adenocarcinoma with an impressive resistance to sequential treatment with ALK TKIs mediated by YES1 and MYC amplification in a contest of epithelial-to-mesenchymal transition and high progressive chromosomal instability.

Methods

The patient received, after chemotherapy and 7 months of crizotinib, brigatinib and lorlatinib with no clinical benefit to both treatments. A study of resistance mechanisms was performed with whole exome sequencing on different biological samples; primary cell lines were established from pleural effusion after lorlatinib progression.

Results

At whole exome sequencing analysis, YES1 and MYC amplifications were observed both in the pericardial biopsy and the pleural effusion samples collected at brigatinib and lorlatinib progression, respectively. Increasing chromosomal instability from diagnostic biopsy to pleural effusion was also observed. The addition of dasatinib to brigatinib or lorlatinib restored the sensitivity in primary cell lines; data were confirmed also in H3122_ALK-positive model overexpressing both YES1 and MYC.

Conclusions

In conclusion, YES1 and MYC amplifications are candidates to justify a rapid acquired resistance to crizotinib entailing primary brigatinib and lorlatinib resistance. In this context, a combination strategy of ALK TKI with dasatinib could be effective to overcome a rapid resistance.

Primary resistance to osimertinib due to SCLC transformation: Issue of T790M determination on liquid re-biopsy

OBJECTIVES

EGFR T790M mutation is the most common mechanism of resistance to first-/second-generation EGFR tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer (NSCLC) and could be overcome by third-generation EGFR-TKIs, such as osimertinib. Liquid biopsy, a non-invasive technique used to test the presence of the resistant mutation, may help avoiding tissue re-biopsy. However, analysing only circulating-free DNA, information about other less frequent and coexisting resistance mechanisms may remain unrevealed.

MATERIALS AND METHODS

All patients reported in this series participated in the ASTRIS trial, a real world treatment study testing the efficacy of osimertinib (80mg os die) in advanced T790M-positive NSCLC progressed to prior EGFR-TKI. Patients were considered eligible to osimertinib if T790M positive on tissue or plasma samples. In our patients, EGFR molecular testing on blood sample was conducted with digital droplet PCR (ddPCR).

RESULTS

We report our experience of five patients treated with osimertinib after T790M detection on liquid biopsy that presented a disease progression at first tumor assessment mediated by SCLC transformation, as evidenced at tissue re-biopsies. All patients showed low ratio T790M/activating mutation in the blood before osimertinib (lower than 0.03). For three patients, EGFR mutational analysis was T790M-negative when re-assessed by using a less sensitive method (therascreen^®) on the same liquid biopsy sample analysed by ddPCR before osimertinib therapy.

CONCLUSION

Although liquid biopsy is a relevant tool to diagnose T790M presence in NSCLC patients resistant to EGFR-TKI, in case of a low ratio T790M/activating mutation, tissue biopsy should be considered to exclude the presence of SCLC transformation and/or other concomitant resistance mechanisms.

RASSF1A promoter methylation and 3p21.3 loss of heterozygosity are features of foregut, but not midgut and hindgut, malignant endocrine tumours

The Ras-association domain family 1A (RASSF1A) tumour suppressor gene is inactivated in a variety of solid tumours, usually by epigenetic silencing of the promoter and/or allelic loss of its locus at 3p21.3. RASSF1A induces cell cycle arrest through inhibition of cyclin D1 accumulation. In this work, 62 endocrine tumours from different sites in the gut were investigated for methylation of the RASSF1A promoter using the polymerase chain reaction, the presence of 3p21.3 deletions by loss of heterozygosity analysis, and cyclin D1 expression by immunohistochemistry. Methylation was found in 20/62 (32%) cases and was restricted to foregut tumours; deletion at 3p21.3 was found in 15/58 (26%) informative cases and restricted to malignant foregut tumours; cyclin D1 hyper-expression was found in 31/58 (53%) cases and correlated with RASSF1A methylation. Our data suggest that RASSF1A is involved in the development of endocrine tumours derived from the foregut only, and that the presence of both RASSF1A methylation and 3p21.3 deletion is associated with malignancy. These results may provide a rationale for foregut-targeted therapy for aggressive endocrine carcinomas entailing the use of demethylating agents.

Progression of gastric enterochromaffin-like cells growth in Zollinger-Ellison syndrome and atrophic body gastritis patients

BACKGROUND

Enterochromaffin-like cell hyperplasia of the gastric body mucosa occurs in hypergastrinaemic conditions such as atrophic body gastritis and Zollinger-Ellison syndrome. However, the time course of change or factors involved are not known.

AIMS

To compare the rate of change of enterochromaffin-like cell proliferation in patients with atrophic body gastritis and Zollinger-Ellison syndrome.

PATIENTS

From a consecutive series of atrophic body gastritis and Zollinger-Ellison syndrome patients, studied at the time of first diagnosis, 10 atrophic body gastritis (4 with pernicious anaemia) and 14 Zollinger-Ellison syndrome (4 with multiple endocrine neoplasia type 1) patients were followed-up for a median time of 48 months.

METHODS

At entry and during follow-up patients underwent: plasma gastrin determination, endoscopic sampling of body mucosa for qualitative assessment of enterochromaffin-like cell hyperplasia pattern and degree of glandular atrophy, qualitative and morphometric analyses of body mucosa endocrine cells.

RESULTS

At time of diagnosis, enterochromaffin-like cell lesions were more severe in atrophic body gastritis than in Zollinger-Ellison syndrome. During follow-up, no significant variations were observed in gastrin values, enterochromaffin-like cell patterns and grade of body mucosa atrophy in atrophic body gastritis. In contrast, gastrin levels were significantly increased [median 1200 (235-2625) vs 1947 (225-5200) pg/ml; p<0.001)] as was total volume density of enterochromaffin-like cells [median 1.60 (0.53-4.06) vs 3.18 (1.35-21.13)% of mucosal epithelial component; (p<0.005)] in Zollinger-Ellison syndrome. Micronodular hyperplasia of enterochromaffin-like cells, present in only one patient at diagnosis, was observed in 8 Zollinger-Ellison syndrome patients at follow-up.

CONCLUSIONS

These data suggest that the progression of enterochromaffin-like cell growth in human gastric mucosa requires an increase of and/or a prolonged exposure to severe hypergastrinaemia.

Atrophic body gastritis patients with enterochromaffin-like cell dysplasia are at increased risk for the development of type I gastric carcinoid

BACKGROUND/AIMS

In the presence of atrophic body gastritis, gastric carcinoid develops from gastric-body mucosa enterochromaffin-like cells. Few data exist on the prevalence of enterochromaffin-like dysplastic lesions in atrophic body gastritis patients and their presumed risk of evolution to carcinoid has never been assessed prospectively in humans. The aim of the present study was to investigate the prevalence and incidence of dysplastic and neoplastic enterochromaffin-like cell lesions in a consecutive series of patients with atrophic body gastritis.

METHODS

A total of 130 atrophic body gastritis patients at diagnosis and 96 atrophic body gastritis patients at follow-up (median 30 months) underwent gastroscopy with multiple biopsies and fasting gastrinaemia evaluation. In patients with enterochromaffin-like cell dysplasia, a more detailed bioptic sampling at follow-up was performed.

RESULTS

Of the 130 atrophic body gastritis patients, only one (0.7%) had a gastric carcinoid polyp, whereas enterochromaffin-like cell dysplasia was found in five patients (3.8%). At follow-up only one out of the 96 atrophic body gastritis patients (1%) was diagnosed as having a carcinoid polyp at 41 months. Enterochromaffin-like cell dysplasia was present in four additional patients (4.2%). Two atrophic body gastritis pernicious anaemia patients with enterochromaffin-like cell dysplasia developed a gastric carcinoid in the follow-up. Among nine atrophic body gastritis patients with enterochromaffin-like cell dysplasia, the incidence of carcinoid tumour was 22% compared to 1.1% of atrophic body gastritis patients without dysplasia (odds ratio: 26.00; 95% confidence interval: 2.089-323.52). During the follow-up, fasting gastrin levels increased significantly only in atrophic body gastritis patients with enterochromaffin-like cell dysplasia (mean 677.4 +/- 66.1 vs 1112.2 +/- 185.6; P = 0.0287).

CONCLUSION

This study provides the first clinical evidence that, in hypergastrinaemic atrophic body gastritis patients, enterochromaffin-like cell dysplasia carries a markedly increased risk for development of type I gastric carcinoid. This suggests that a more detailed endoscopic/bioptic procedure in this subgroup of atrophic body gastritis patients is able to detect gastric carcinoid at an early stage.

p27: a potential main inhibitor of cell proliferation in digestive endocrine tumors but not a marker of benign behavior

The immunohistochemical expression of the inhibitors of cyclin-dependent kinases p21 and p27 was investigated in 109 endocrine tumors of the pancreas and gastrointestinal tract and compared with that of Ki67 and p53. p21 was found to be scarcely expressed without significant differences between benign and malignant or between differentiated and undifferentiated tumors. This suggests no relationship between changes in p21 levels and clinical behavior in these endocrine tumors. p27 was found to be highly expressed in differentiated neoplasms and proved to be inversely related to Ki67 labeling (P =.02), which was usually low. These data indicate that p27 may have an important inhibiting role on the low proliferation rate of the tumors. Moreover, the protein may have a role in the resistance of differentiated endocrine tumors to chemotherapeutic agents. p27 high-expressor neoplasms were frequent in either benign (70.6%) or malignant (81.4%) differentiated tumors, thus not allowing the use of this protein for the differential diagnosis of malignant neoplasms as suggested for endocrine tumors of parathyroid and pituitary. Poorly differentiated endocrine carcinomas, which differred from the differentiated tumors for their very high Ki67 levels and frequent p53 expression, showed low or absent p21 and p27 in most cases. Classical midgut carcinoids were characterized by a sharp discrepancy between malignant behavior and very bland proliferative pattern, with Ki67 and p27 expressions similar to that of benign tumors.

The antral mucosa as a new site for endocrine tumors in multiple endocrine neoplasia type 1 and Zollinger-Ellison syndromes

Carcinoid tumors were identified in the antro-pyloric mucosa of four patients with multiple endocrine neoplasia type 1 (MEN-1)/Zollinger-Ellison syndrome, accounting for 8.7% of 46 patients with this condition examined by endoscopy and histology. In contrast, no tumors were found in the antral biopsies from 124 cases of sporadic Zollinger-Ellison syndrome (P < 0.001), indicating a prominent role for the MEN-1 gene defects in tumor development. Immunohistochemically the tumors did not express the hormones produced by antral endocrine cells (gastrin, somatostatin, serotonin). In contrast, two of them were diffusely immunoreactive for the isoform 2 of the vesicular monoamine transporter (VMAT-2), a marker specific for the gastric nonantral enterochromaffin-like (ECL) cells. In one of these patients a second antral VMAT-2-positive carcinoid was seen 21 months after the first diagnosis. The other two antral carcinoids were unreactive for VMAT-2. Multiple ECL cell tumors were found in the gastric body-fundus mucosa of the two patients with VMAT-2-positive, but not in those with VMAT-2-negative, antral carcinoids. In one case, the former tumors were diagnosed 22 months after the detection of the antral tumor. We conclude that the antral mucosa is an additional tissue that may harbor endocrine tumors in MEN-1 syndrome. These tumors did not express the phenotype of normal antral endocrine cells and, in at least two cases, were identified as ectopic ECL cell carcinoids.

Sampling strategies for analysis of enterochromaffin-like cell changes in Zollinger-Ellison syndrome

To investigate the optimum number of biopsy specimens to be obtained for enterochromaffin-like (ECL) cell monitoring in hypergastrinemic patients and ECL cell regional variations potentially influencing the results, qualitative ECL cell changes were assessed in 149 patients with Zollinger-Ellison syndrome using jumbo biopsy specimens and a systematic sampling procedure of 4 areas each from the lesser or greater curvature of the gastric body. Of 1,176 specimens examined, 1,101 were adequate. The correlation was excellent between different sites within the greater or lesser curvature. In contrast, a normal ECL cell pattern was more frequent in the lesser curvature, whereas linear hyperplasia was more frequent in the greater curvature. Dysplastic lesions and carcinoid tumors in endoscopically unremarkable mucosa were detected in 3.4% and 1.2% of biopsy specimens, respectively, and were equally distributed between the lesser and greater curvature. Their chances of being diagnosed were related to the number of specimens examined. Extensive sampling of both the lesser and greater curvature is recommended for early diagnosis of dysplastic and/or carcinoid lesions in patients at risk. In contrast, limited sampling in the greater curvature seems to be adequate in patients with no risk for carcinoid development.

Classification of gastric endocrine cells at the light and electron microscopical levels

This review discusses the current concepts for the classification of gastric endocrine cells subdivided according to the type of mucosa in which they are located. In the oxyntic mucosa, the most important cell type is the ECL cell, involved in the synthesis and secretion of histamine. Proteins involved in many aspects of the biology of ECL cells including the response to the gastrin stimulus, membrane transport and docking, prevention of apoptosis, calcium homeostasis, autocrine activity, and maintenance of the differentiated cell phenotype have been localized to this cell type. Other cells of the oxyntic mucosa include: the D and EC cells producing somatostatin and serotonin, respectively, delivered through long cell processes; the X (or A-like) cells, possibly producing endothelin; and the D(1) and P cells of unknown function and possibly representing morphological variants of other cell types. In the antral mucosa, the three important cell types are represented by: the gastrin-producing G cells; the somatostatin-producing D cells, which are anatomically and functionally associated with G cells; and the serotonin-producing EC cells, which are located at the bottom of antral glands.

Classification of gastric endocrine cells at the light and electron microscopical levels

This review discusses the current concepts for the classification of gastric endocrine cells subdivided according to the type of mucosa in which they are located. In the oxyntic mucosa, the most important cell type is the ECL cell, involved in the synthesis and secretion of histamine. Proteins involved in many aspects of the biology of ECL cells including the response to the gastrin stimulus, membrane transport and docking, prevention of apoptosis, calcium homeostasis, autocrine activity, and maintenance of the differentiated cell phenotype have been localized to this cell type. Other cells of the oxyntic mucosa include: the D and EC cells producing somatostatin and serotonin, respectively, delivered through long cell processes; the X (or A-like) cells, possibly producing endothelin; and the D(1) and P cells of unknown function and possibly representing morphological variants of other cell types. In the antral mucosa, the three important cell types are represented by: the gastrin-producing G cells; the somatostatin-producing D cells, which are anatomically and functionally associated with G cells; and the serotonin-producing EC cells, which are located at the bottom of antral glands.

Classification of gastric endocrine cells at the light and electron microscopical levels

This review discusses the current concepts for the classification of gastric endocrine cells subdivided according to the type of mucosa in which they are located. In the oxyntic mucosa, the most important cell type is the ECL cell, involved in the synthesis and secretion of histamine. Proteins involved in many aspects of the biology of ECL cells including the response to the gastrin stimulus, membrane transport and docking, prevention of apoptosis, calcium homeostasis, autocrine activity, and maintenance of the differentiated cell phenotype have been localized to this cell type. Other cells of the oxyntic mucosa include: the D and EC cells producing somatostatin and serotonin, respectively, delivered through long cell processes; the X (or A-like) cells, possibly producing endothelin; and the D(1) and P cells of unknown function and possibly representing morphological variants of other cell types. In the antral mucosa, the three important cell types are represented by: the gastrin-producing G cells; the somatostatin-producing D cells, which are anatomically and functionally associated with G cells; and the serotonin-producing EC cells, which are located at the bottom of antral glands.

Intramucosal cysts in the gastric body of patients with Zollinger-Ellison syndrome

To ascertain the frequency and the clinico-functional correlations of intramucosal cysts in the gastric body of patients with the Zollinger-Ellison syndrome (ZES) and to clarify the relevant mechanism of development, a total of 106 consecutive ZES patients (58 M, 48 F; mean age: 53 yrs, range 19-93 yrs) were investigated with a mean of 7.2 biopsy specimens of the body mucosa per patient proved to be suitable for the study. Biopsies of endoscopically detectable polypoid lesions were not considered. Cystic changes were evaluated with respect to their severity by assessing the cyst grade (0, absent, 1; <30%, 2; 30-60%; 3 >60% of the mucosal area of the biopsy specimen of individual patients showing the most pronounced finding, respectively) and to their intragastric distribution by assessing the ratio of biopsy specimens showing cystic changes over the total number of biopsies examined in each patient. Intramucosal cysts were found in biopsies of non-polypoid gastric body mucosa in 71.7% of 106 patients with Zollinger-Ellison syndrome (ZES) and showed grade 2 and 3 severity in 22 and 8 cases, respectively. The severity of cystic changes correlated with the gastrin levels (p = 0.0005) and was more advanced in patients with active than in those with cured disease (p = 0.037). In the former group, furthermore, advanced cystic changes correlated with age (p = 0.03), male gender (p = 0.014), years of disease from onset (p < 0.02), years of omeprazole treatment (p = 0.033), basal acid output (p < 0.02), severity of ECL cell proliferative changes (p = 0.028), and absence of previous gastrinoma resection (p = 0.039) whereas they did not correlate with MEN-1 status, gastritis, maximal acid output, total duration of any antisecretory drug treatment, daily doses of omeprazole (> 20 mg vs 20 mg), years from surgery, duodenal localization of gastrinoma(s), presence of gastric carcinoid tumor(s) and of liver metastases. In groups of patients subdivided according to three levels of serum gastrin, the duration of omeprazole treatment was not related to the severity of cystic changes. It is concluded that intramucosal cysts in non polypoid gastric body mucosa of ZES patients are by far more common than the already reported fundic gland polyps, to which they likely give raise. Circulating levels of gastrin have an important independent role in their development.

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.

Functioning human insulinomas. An immunohistochemical analysis of intracellular insulin processing

Sixty-seven insulinomas were investigated by immunohistochemistry using site-directed antibodies against insulin, proinsulin, chromogranin A, HISL-19, and four proteins directly or indirectly involved in the proteolytic processing of proinsulin: the prohormone convertases PC2 and PC3, carboxypeptidase H (CPH) and 7B2. Results were expressed in a six-grade score according to the frequency of immunoreactive tumour cells. Insulin was expressed by all tumours, appearing in either a diffuse or a polarized pattern and being detected in more than 30% of tumour cells in all cases but three. Proinsulin was also expressed in all tumours, with more than 50% of tumour cells immunoreactive in all cases but 5. It was consistently localized in the Golgi apparatus. In about half the cases, moreover, it also showed diffuse cytoplasmic staining, usually with a very sparse distribution. Trabecular and solid insulinomas did not present specific, homogeneous patterns of insulin immunostaining. However, insulin immunoreactivity was much more abundant in trabecular than in solid neoplasms, being present in virtually all tumour cells (score 6) in 50% and 8% of cases, respectively. Virtually all insulinomas expressed PC2, PC3, CPH and 7B2, usually in 30-100% of tumour cells, with a frequency significantly related to that of insulin. However, detection of PC2 and 7B2 was slightly less frequent than that of PC3 and CPH. In consecutive sections these proteins were found to be mostly co-localized with insulin and chromogranin A but not with proinsulin. They were heavily expressed in all 10 tumours with more than 10% of cells showing cytoplasmic proinsulin immunoreactivity, indicating that the leakage of proinsulin from the Golgi compartment is not associated with faulty expression of converting enzymes and possibly reflects a saturated processing capacity. HISL-19 immunoreactivity was found in both Golgi apparatus and insulin stores, indicating that the relevant antigen is different from all other proteins investigated. These results do not support a defect in expression or localization of proinsulin-processing enzymes in most insulinomas.

Expression of the alpha- and beta-subunits of human chorionic gonadotropin by subsets of parathyroid cells in states of hyperparathyroidism

The alpha-subunit of human chorionic gonadotropin (hCG-alpha) has previously been found to be expressed in hyperplasias and tumours of numerous endocrine tissues including all those involved in MEN-I syndrome except the parathyroid glands. In the present immunohistochemical investigation of 86 patients with various states of hyperparathyroidism, expression of hCG-alpha by subsets of parathyroid cells was shown in 46 cases (54 per cent) including all states of hyperparathyroidism investigated: primary adenoma (n = 34, 44 per cent); uraemic secondary hyperplasia (n = 34, 53 per cent); MEN-I (n = 13, 77 per cent); MEN-II (n = 2, 100 per cent); and parathyroid carcinoma (n = 3, 100 per cent). Although the number of parathyroid cells expressing hCG-alpha was in general low, the occurrence of numerous immunoreactive cells appeared to be concentrated in primary adenoma and MEN-I (20 and 33 per cent of positive cases, respectively). No expression was found in ten normal control glands, except for very rare cells in one case. Expression of hCG-alpha was in part associated with that of hCG-beta, which appeared to be more commonly expressed than hCG-alpha in cases of secondary hyperparathyroidism. In separate experiments, Bouin fixation was found to preserve the immunoreactivity of hCG-alpha and hCG-beta better than the formalin fixation used in this study, suggesting that the figures may be underestimates. These immunohistochemical results are in agreement with a previous biochemical study showing hCG-alpha and hCG-beta in extracts of parathyroid tumours and extend to the parathyroid glands the otherwise ubiquitous finding of hCG-alpha expression in MEN-I-related neoplasms.

Neuroendocrine proliferation in the gastric mucosa: biological behaviour and management

Neuroendocrine proliferation of gastric mucosa is commonly encontered in routine gastric biopsies and is an indirect effect of modern drugs suppressing acid secretion. The process is virtually circumscribed to the ECL cell, the most common endocrine cell of the oxyntic mucosa, and is dependent on the trophic effect of the concomitant hypergastrinemia in most cases. It starts in the form of hyperplastic lesions that in some cases evolves into dysplasia and neoplasia. Gastrin has promoting but not transforming properties for such ECL cell tumour induction. Proven or potential transforming factors include the allelic loss of the MEN-1 suppressor gene at 11q13, the still unknown factor(s) associated with atrophic corporal gastritis in which overexpression of BCL-2 likely plays a favouring role by prolonging ECL exposure to mitogens, and agents with still unclarified role, such as basic fibroblast growth factor, human chorionic gonadotropin-alpha and transforming growth factor-alpha. Gastric neuroendocrine tumours independent of the trophic effect of gastrin are less frequent but more malignant. Their pathogenesis and precursor lesions are ignored.

Pathogenesis of ECL cell tumors in humans

In ECL cell tumors developed in the setting of hypergastrinemic conditions (ECL cell carcinoids type 1 and 2), hypergastrinemia is the dominant agent acting as a promoter in all steps (hyperplasia-dysplasia-neoplasia) of the tumorigenic sequence. In contrast, it apparently lacks transforming properties as shown by the absence of ECL cell carcinoids in patients exposed to hypergastrinemia alone, i.e., those with sporadic Zollinger-Ellison syndrome. The potential transforming factors include: the allelic loss of the MEN-1 suppressor gene in the genetically predisposed MEN-1 patients, an alteration that may induce ECL cell tumors even in the absence of hypergastrinemia; the still unknown factor(s) associated with atrophic corporal gastritis; agents whose role in the induction of human ECL cell tumors is still unclarified, such as basic Fibroblast Growth Factor, human Chorionic Gonadotropin-alpha and Transforming Growth Factor-alpha; and agents having a favoring role on the ECL exposure to mitogens such as BCL-2. No information is currently available on the pathogenesis of gastrin-independent, sporadic ECL cell carcinoids (type 3) or of gastric neuroendocrine carcinomas.

Endocrine cell growths in atrophic body gastritis. Critical evaluation of a histological classification

The aim of the present study was to evaluate the correspondence of the classification of non-antral endocrine cell growths proposed by Solcia and co-workers with clinical features and non-endocrine mucosal changes. For this purpose, 94 cases of newly diagnosed atrophic body gastritis were investigated using endoscopic biopsies and compared with 18 control subjects. The patients were subdivided into the following four groups according to the most severe pattern of endocrine cell proliferation found in the body mucosa, as shown by chromogranin A immunostaining: group 1, normal pattern (7 cases, 7.5 per cent); group 2, simple hyperplasia (6 cases, 6.5 per cent); group 3, linear hyperplasia (24 cases, 25.8 per cent); group 4; micronodular hyperplasia (56 cases, 60.2 per cent). Adenomatoid hyperplasia was found in only one case, thus precluding further analysis. Patients in groups 1 and 2 had lower acid secretion, higher gastrin level, and higher mean scores in all histopathological variables of chronic gastritis considered by the Sydney system when compared with controls, but did not differ among them in any parameter investigated. When compared with groups 1 and 2, patients of groups 3 and 4 showed higher values of circulating gastrin, higher scores of glandular atrophy, and lower values of acid secretion and of mononuclear and neutrophil inflammatory cell infiltration. Moreover, group 4 patients differed significantly from those of group 3 in their higher gastrin levels and atrophy scores, and lower scores of neutrophil cell infiltration. On the basis of these results, it is proposed that for practical purposes the normal and the simple hyperplasia patterns may be incorporated into a single group. It is concluded that this classification in its simplified form, based on a qualitative histological approach, shows clinical relevance without the need to perform expensive, time-consuming morphometric evaluations.

Aggressive forms of gastric neuroendocrine tumors in multiple endocrine neoplasia type I

In recent classifications of gastric endocrine tumors, tumors arising in patients with multiple endocrine neoplasia type 1 (MEN-1) are regarded to be regulated by the concomitant hypergastrinemia resulting from to pancreatic or, most commonly, duodenal gastrinomas and to have a benign behavior. In this article, we report on two cases of MEN-1 gastric neuroendocrine tumors having a fatal course. Case 1 was a young male with hyperparathyroidism and Zollinger-Ellison syndrome and with florid development of multiple gastric carcinoids and multiple duodenal gastrinomas. Metastases occurred in the liver, of exclusive gastric origin, in periduodenal lymph nodes, of exclusive duodenal origin, and in perigastric lymph nodes, of mixed origin. The patient died 48 months after diagnosis. Case 2 was an adult female patient with hyperparathyroidism, adrenocortical disorders, and gastric tumors but no hypergastrinemia. The patient died 3 months after tumor diagnosis. At autopsy, the stomach showed multiple benign carcinoids and two independent neuroendocrine carcinomas not reported before in MEN-1 and massively metastatizing to lymph nodes, liver, and peritoneum. Multiple islet cell tumors mostly producing pancreatic polypeptide were found, whereas gastrinomas were seen in neither the pancreas nor the duodenum. Allelic losses at the MEN-1 gene locus in chromosome 11q13, the mechanism responsible for tumor development in MEN-1 syndrome, were demonstrated in the carcinoid tumors of case 1 and in the neuroendocrine carcinoma of case 2. We conclude that gastric neuroendocrine tumors in patients with MEN-1 may have a poor outcome, they have the same genetic mechanism as MEN-1 tumors in other organs, and they may be independent of the trophic effect of hypergastrinemia.

[Neuroendocrine tumors of the stomach. Pathogenesis, classification and clinical aspects]

Neuroendocrine tumors of the stomach are classified into four types mostly on the basis of their pathological associations: 1) carcinoid type I, associated with atrophic corporal gastritis, 2) carcinoid type II, associated with multiple endocrine neoplasia type 1, 3) carcinoid type III, sporadic, and 4) neuroendocrine carcinoma. The first two types develop through a histologically recognizable sequence hyperplasia--dysplasia--neoplasia. Their pathogenesis depends on the combined action of promoting agents, mostly hypergastrinemia, and of transforming agents, the role of which is currently under investigation. Their prognosis is generally favourable in sharp contrast with that of the other two types of tumors, which is usually poor. The pathogenesis and the precursor lesions of the latter neoplasms have not been clarified yet.

Endocrine cell growths in atrophic body gastritis. Critical evaluation of a histological classification

The aim of the present study was to evaluate the correspondence of the classification of non-antral endocrine cell growths proposed by Solcia and co-workers with clinical features and non-endocrine mucosal changes. For this purpose, 94 cases of newly diagnosed atrophic body gastritis were investigated using endoscopic biopsies and compared with 18 control subjects. The patients were subdivided into the following four groups according to the most severe pattern of endocrine cell proliferation found in the body mucosa, as shown by chromogranin A immunostaining: group 1, normal pattern (7 cases, 7.5 per cent); group 2, simple hyperplasia (6 cases, 6.5 per cent); group 3, linear hyperplasia (24 cases, 25.8 per cent); group 4; micronodular hyperplasia (56 cases, 60.2 per cent). Adenomatoid hyperplasia was found in only one case, thus precluding further analysis. Patients in groups 1 and 2 had lower acid secretion, higher gastrin level, and higher mean scores in all histopathological variables of chronic gastritis considered by the Sydney system when compared with controls, but did not differ among them in any parameter investigated. When compared with groups 1 and 2, patients of groups 3 and 4 showed higher values of circulating gastrin, higher scores of glandular atrophy, and lower values of acid secretion and of mononuclear and neutrophil inflammatory cell infiltration. Moreover, group 4 patients differed significantly from those of group 3 in their higher gastrin levels and atrophy scores, and lower scores of neutrophil cell infiltration. On the basis of these results, it is proposed that for practical purposes the normal and the simple hyperplasia patterns may be incorporated into a single group. It is concluded that this classification in its simplified form, based on a qualitative histological approach, shows clinical relevance without the need to perform expensive, time-consuming morphometric evaluations.

Atrophic body gastritis: distinct features associated with Helicobacter pylori infection

BACKGROUND

Usually, atrophic body gastritis has been considered an autoimmune disease characterized by the presence of parietal cell antibodies. Previous investigations into the role of Helicobacter pylori infection have obtained conflicting results. The aim of this study was to investigate the prevalence and role of H. pylori in a prospectively investigated population of patients with corpus-predominant atrophic gastritis.

PATIENTS AND METHODS

A consecutive series of 67 newly diagnosed cases of atrophic body gastritis was derived from a screening of 326 patients with unexplained anemia or dyspepsia. Criteria for diagnosis were fasting hypergastrinemia, pentagastrin-resistant achlorhydria, and histological confirmation of body atrophy. In all 67 patients, H. pylori infection was evaluated independently by histological assay and urease test. The gastritis status of both the fundic and antral mucosa were graded according to the Sydney system. Parietal cell and intrinsic factor antibodies also were determined.

RESULTS

Active H. pylori infection was present in 26.8% of our patients and allowed us to identify a patient's subpopulation with a significantly smaller degree of body mucosa damage as shown by functional parameters (gastrin, gastric acid secretion, pepsinogen I) and histological assessment. In this subpopulation, a higher prevalence of gastric cancer familial history was found. Presence of parietal cell antibodies showed a similar prevalence in H. pylori-positive and H. pylori-negative patients (61.1% vs. 69.4%) and was not associated with significant functional and histological differences. Cure of infection determined an evident improvement of corporal atrophy as well as a reduction of hypergastrinemia.

CONCLUSION

Active H. pylori infection, a potential cause of oxyntic gland atrophy, is found in one-fourth of patients with newly diagnosed atrophic body gastritis.

Pancreatic-polypeptide cell hyperplasia associated with pancreatic or duodenal gastrinomas

An immunohistochemical investigation of pancreatic-polypeptide (PP) cells in the PP-rich region of the pancreas, of ventral embryological origin, was performed in three female patients affected by or previously operated on for functioning duodenal or pancreatic gastrinomas not associated with multiple endocrine neoplasia syndrome. A pronounced PP-cell hyperplasia showing histological patterns of endocrine cell dysplasia and focal adenomatosis as defined by Jaffe et al was found in all cases. Morphometric analysis showed that in these patients the fraction of ventral-type pancreatic lobules occupied by PP-immunoreactive cells was 14.77 +/- 5.73%, 8.94 +/- 2.92%, and 10.83 +/- 5.64%, respectively. These values were three to five times higher than the upper values found in controls (mean, 2.20%; range, 1.54 to 2.93%; P < .0001). PP-cell hyperplasia may contribute for the increased circulating levels of PP found in gastrinoma patients. In this regard, elevation of fasting blood PP was found in one of four determinations done in one patient, indicating that PP-cell hyperplasia may be responsible for, at least, transient PP hypersecretion. In one of our patients, PP-cell hyperplasia was found 15 years after normalization of gastrin levels by removal of a single pancreatic gastrinoma. This finding is against a trophic role for hypergastrinemia in the development of PP-cell hyperplasia. In one of two patients in whom the pancreatic regions of dorsal embryological origin (ie, body and tail of the gland) were examined, ventral-type, PP-rich islets were frequently encountered, a finding at variance with their exceptional detection in control cases. This finding suggests that PP cell hyperplasia of the PP-rich pancreatic region may be a feature of a more diffuse disorder of PP cell development in the pancreas of gastrinoma patients.

Involvement of BCL-2 oncoprotein in the development of enterochromaffin-like cell gastric carcinoids

To evaluate the involvement of the apoptosis-suppressing protein BCL-2 in the gastrin-dependent mechanism of induction of gastric enterochromaffin-like (ECL) cell carcinoids, the endocrine cell of the oxyntic mucosa were immunohistochemically investigated in (a) 10 normogastrinemic subjects with histologically normal gastric mucosa; (b) 22 patients with endocrine cell hyperplasia and affected by hypergastrinemic conditions with different risk of gastric carcinoid development, such as sporadic Zollinger-Ellison syndrome (sZES; n = 9), ZES associated with multiple endocrine neoplasia-1 (MEN-1; n = 4), and atrophic fundal gastritis (AFG; n = 9); (c) 14 patients with ECL gastric carcinoids accounting for a total of 31 tumors investigated. In the normal oxyntic mucosa, BCL-2 was consistently expressed by a subset of endocrine cells accounting for 50.0% (median; range, 24.6-74.0%) of the total number of endocrine cells immunostained for chromogranin A (CgA) in consecutive sections. BCL-2 immunoreactive cells were located mostly in the middle mucosal layer, suggesting a role for the protein during downward migration of maturing endocrine cells. No BCL-2 immunoreactivity was found in other specialized gastric epithelial cells. Expression of BCL-2 by hyperplastic oxyntic endocrine cells (mostly ECL cells) varied in parallel with the risk of carcinoid development. In fact, the ratio of BCL-2- to CgA-immunoreactive cells was reduced (median, 4.6%; p less than 0.0001; range, 0.9-42.0%) in sZES, a condition showing virtually no risk, unchanged (median, 55.6%; range 29.4-83.8 %) in cases of MEN-1/ZES with intermediate risk, and increased (median 87.6%; p less than 0.014; range, 48.8-199.4%) in cases of AFG, a condition at the highest risk of carcinoid. In ECL cell carcinoids, BCL-2 expression varied markedly from one tumor to another even in the same patient and was low or absent in most cases. In both hyperplastic and neoplastic ECL cells, an inverse relation between BCL-2 expression and CgA immunoreactivity, that is, the cell granule content, was found. These results suggest that BCL-2 expression by hyperplastic ECL cells is independent of the influence of serum gastrin and may contribute to the development of ECL cell carcinoid tumors by extending cell exposure to oncogenic factors. Once a carcinoid tumor is established, BCL-2 expression becomes inconsistent.

Effectiveness of octreotide in controlling fasting hypergastrinemia and related enterochromaffin-like cell growth

The effects of long term (6-month), high (500-micrograms), once a day administration of octreotide on enterochromaffin-like (ECL) cell proliferation were evaluated in eight patients with hypergastrinemic atrophic gastritis at risk for the development of gastric carcinoids. Fasting gastrin levels were determined during treatment and up to 6 months after the end of treatment. Chromogranin A, hCG alpha, and somatostatin-immunostained cells were morphometrically evaluated in biopsy specimens of corpus mucosa taken before and after treatment. The results showed that gastrin levels significantly decreased from 950 to 238 ng/L (-74.9%; P < 0.01) at the end of treatment, a decrease that persisted 6 months after the end of treatment (450 ng/L; P < 0.05). The volume density of CgA cells (mostly ECL cells) decreased from 3.7% to 2.1% of the epithelial component (-43%; P < 0.014), that of hCG alpha-storing ECL cells decreased by 85% (P < 0.0007), and that of somatostatin-stained cells decreased by 74% (P < 0.04). No clinically significant side-effects were found. It is concluded that octreotide treatment as used in the present study is safe and effective in reducing hypergastrinemia and associated ECL cell changes in patients with atrophic gastritis. The decrease in D cells is consistent with the occurrence of somatostatin receptors and related autocrine regulation in these cells.

Well-differentiated endocrine tumours of the middle ear and of the hindgut have immunocytochemical and ultrastructural features in common

The immunocytochemical analysis of two cases of well-differentiated endocrine tumours (carcinoids) of the middle ear revealed predominant cell populations producing pancreatic polypeptide (PP)-related peptides, glucagon-related peptides, and serotonin (the latter only in one case). In consecutive sections PP- and glucagon-related immunoreactivities mainly colocalized in the same tumour cells. Ultrastructurally tumour cells were characterized by medium-sized to large granules of moderate to high density, on which PP and glicentin were localized by the immunogold technique. No amphicrine cells were found. These features are consistent with those of similar tumours in the rectal mucosa that are mainly composed of L cells coexpressing both PP-related and glucagon-related peptides. Additional tumour antigens of hindgut type detected immunohistochemically were prostatic acid phosphatase and CAR-5 mucin. Expression of the CAR-5 antigen was also found in samples of normal middle ear mucosa, in which endocrine cells have not been identified. In case 1 peritumoral mucosal invaginations showed a proliferation of endocrine cells identical immunophenotypically to tumour cells, possibly representing a precursor lesion. It is concluded that well-differentiated endocrine tumours of the middle ear are a distinct pathological entity characterized by multiple hormone production, typically involving three classes of hormones (pancreatic polypeptide-related peptides, glucagon-related peptides, and serotonin) of the hindgut endocrine system.

Lack of allelic loss at the multiple endocrine neoplasia type 1 (MEN-1) gene locus in a pancreatic ductal (non-endocrine) adenocarcinoma of a patient with the MEN-1 syndrome

The gene responsible for multiple endocrine neoplasia type I (MEN-1) syndrome has been mapped to chromosome 11q13. It appears to function as a tumour-suppressor gene analogous to that for retinoblastoma and allelic losses involving the wild-type of the MEN-1 allele have been found in parathyroid and pancreatic endocrine tumours of MEN-1 patients. No genetic information has been provided so far on non-endocrine malignancies that may occur in MEN-1 patients. A case of exocrine pancreatic adenocarcinoma presenting as the terminal event in a woman with a long standing history of MEN-1 syndrome and multiple endocrine tumours of the pancreas was investigated for possible allelic losses at the MEN-1 gene locus using restriction fragment length polymorphisms (RFLPs) closely linked to the MEN-1 gene and polymerase chain reaction (PCR) for D11S533 locus. No allelic losses were found in tumour tissue with two informative RFLPs (D11S97, D11S146) or with PCR analysis. These findings suggest that the MEN-1 gene does not confer a predisposition to develop tumours other than those that typify the syndrome.

Gastric carcinoid tumor and its precursor lesions. Ultrastructural study of a case before and after antrectomy

Antrectomy has been proposed as the preferential treatment of hypergastrinemic patients with nonantral gastric carcinoids since it removes the main growth factor for the tumors and their precursor lesions, ie, hypergastrinemia. To investigate the cellular basis of the mechanism for postantrectomy regression in nonantral endocrine cells, a light and electron microscopic morphometric study was performed in a case of enterochromaffinlike-cell gastric carcinoid associated with hypergastrinemia before and 4 and 10 months after antrectomy. The withdrawal of sustained hypergastrinemia obtained by antrectomy was associated with a progressive reduction of the volume density, cross-sectional area, and number of profiles of endocrine cells in the remaining nonantral mucosa, in which gastrin-dependent proliferations were regarded as the carcinoid precursor lesions. Ultrastructural morphometry demonstrated that the changes selectively involved the enterochromaffinlike cells, ie, the specific cell target for the trophic action of gastrin and the usual component of gastric carcinoids. The volume fractions of enterochromaffin and X cells (producing serotonin and endothelin, respectively) were increased 10 months after antrectomy. Persistence of a modest elevation of gastrin levels, likely due to the occurrence of gastrin cells in areas of pyloric metaplasia of the nonantral mucosa, did not prevent the hypotrophic effects of antrectomy.

Three months of octreotide treatment decreases gastric acid secretion and argyrophil cell density in patients with Zollinger-Ellison syndrome and antral G-cell hyperfunction

METHODS

The effects of three months of treatment with octreotide on gastric acid hypersecretion induced by hypergastrinaemia were investigated in patients with Zollinger-Ellison syndrome (n = 5) or antral G-cell hyperfunction (n = 4). Gastric acid secretion, fasting plasma gastrin concentrations and clinical findings were examined, and a morphometrical analysis of oxyntic endocrine cells was performed.

RESULTS

Administration of octreotide 100 mcg b.d. subcutaneously significantly decreased the volume density of argyrophil cells (P < 0.05) as well as basal and pentagastrin-stimulated acid secretion (P < 0.05). Although partial or complete loss of inhibition was found in most patients after 3 months, gastrin levels were decreased during the first 2 months of treatment (P < 0.05). Fundic D-cells were not affected by treatment. Positive correlations were observed between volume density of argyrophil cells and basal acid output (r = 0.65); plasma gastrin and basal acid output (r = 0.74); plasma gastrin concentrations and volume density of argyrophil cells (r = 0.80).

CONCLUSION

These results support the important role of the enterochromaffin-like cell in maintaining acid secretion, and indicate a specific role for octreotide in the therapy of gastric acid hypersecretion associated with hypergastrinaemic diseases.

Production of basic fibroblast growth factor by gastric carcinoid tumors and their putative cells of origin

Using immunohistochemical techniques a subpopulation of endocrine cells in the human oxyntic mucosa was found to react with antibodies against basic fibroblast growth factor (bFGF). These cells were identified as histamine-producing enterochromaffin-like (ECL) cells and, to a minor extent, serotonin-producing enterochromaffin cells. Basic fibroblast growth factor immunoreactive cells were most frequently found in hyperplastic lesions of ECL cells occurring in hypergastrinemic patients (20 of 27 cases) and in ECL cell carcinoid tumors (10 of 17 cases). In addition, bFGF mRNA was demonstrated by Northern blot analysis of homogenates from two gastric carcinoids cytologically characterized as pure ECL cell tumors. Although the function of bFGF in normal cells remains unknown, its production in neoplastic conditions may be responsible for the associated desmoplastic and angioblastic proliferations. Moreover, secretion of bFGF by hyperplastic or neoplastic ECL cells may contribute to the circulating levels of the bFGF-like mitogenic factor identified in patients affected by multiple endocrine neoplasia type 1 syndrome.

Morphometry of gastric endocrine cells in hypergastrinemic patients treated with the somatostatin analogue octreotide

The aim of the study was to evaluate whether treatment with 200 micrograms/d of the somatostatin analogue octreotide (SMS 201-995) for three months can influence the trophic action exerted by hypergastrinemia on endocrine cells of the oxyntic mucosa, a condition potentially leading to hyperplasia and carcinoid tumors. Endocrine cells were morphometrically investigated in Grimelius silver stained sections of endoscopic biopsies of oxyntic mucosa collected from 13 hypergastrinemic patients with Zollinger-Ellison syndrome (ZES) (n = 5), antral G cell hyperfunction (AGCH) (n = 4) and atrophic gastritis type A (AG-A) (n = 4) before and after 3 months treatment and 3 months after drug discontinuance. The treatment induced a reduction of the volume density (P < 0.015), profile cross sectional area (P < 0.05) and number of cell profiles per unit area (P < 0.015) of argyrophil cells. A rebound of all these parameters was observed 3 months after drug withdrawal with values usually exceeding those at the entry, except in cases of AG-A. The patients' plasma gastrin concentrations presented similar variations showing a significant relation with all morphometric parameters of argyrophil cells. Also, the cell content in alpha subunit of human chorionic gonadotropin was related to the plasma gastrin levels, a finding confirming the close gastrin dependence of the expression of this protein by oxyntic endocrine cells. No significant changes were observed in mucosal somatostatin D cells. These results indicate that variations in circulating gastrin levels are the most likely factor responsible for the hypotrophic effect of octreotide on oxyntic argyrophil cells (mostly corresponding to the ECL cells) of hypergastrinemic patients.

Studies on co-localization of 7B2 and pancreatic hormones in normal and tumoural islet cells

The distribution of protein 7B2, a protein with structural characteristics of GTP-binding proteins, has been studied in normal pancreatic islets and in a series of 70 pancreatic endocrine tumours with emphasis on the co-localization of 7B2 and the different pancreatic hormones. Although all cell types of normal islets were found to store 7B2, variations from intense expression to absence of reaction were seen within each cell type. In particular, B cells showed intense immunostaining for 7B2 in small compact islets and weak or no staining in larger islets with lobular arrangement. Pancreatic polypeptide (PP) cells expressed 7B2 intensely in the PP-rich area of ventral embryological origin, but were mostly non-reactive in the PP-poor area. The A cells, located along intralobular blood vessels, were more frequently immunoreactive for 7B2 than those at the periphery of the islets. Immuno-electron microscopy revealed a preferential localization of 7B2 in secretory granules of islet cells, with more intense localization in the peripheral halo of alpha granules. Benign islet cell tumours more frequently expressed 7B2 than their malignant counterparts. Although often expressed in a lower number of tumour cells than the tumour-specific hormone, 7B2 was usually co-localized with the latter. In contrast, no relationship was found with the localization of proinsulin. It is concluded that 7B2 is a non-permanent component of the cell granule compartment, probably involved in events related to exocytosis and without relationship to intracellular prohormone processing.

Focal oxyntic gland atrophy with endocrine cell hyperplasia in Zollinger-Ellison syndrome during omeprazole treatment

Development of focal gland atrophy of the oxyntic mucosa was found in two patients with the Zollinger-Ellison syndrome undergoing long-term treatment with omeprazole. The atrophic areas revealed florid proliferation of endocrine cells in the form of both intraglandular crescents and micronodular hyperplasia. This proliferation was significantly more pronounced than in the remaining non-atrophic mucosa. The possible relationship of these changes to long-standing pharmacological therapy for gastric acid suppression is discussed.

Malignant enterochromaffinlike cell carcinoid of the gastric stump: an ultrastructural study

A metastasizing carcinoid of the gastric stump found 25 years after Billroth II gastric resection for duodenal ulcer is described. Electron microscopy and optical endocrine cell staining proved the tumor to be composed of enterochromaffinlike (ECL) cells. This unusual combination further shows that, at variance with most of these tumors, ECL cell carcinoids may develop also in a condition excluding a trophic effect of gastrin. This case emphasizes the malignant behavior of gastrin-independent ECL cell tumors.