Endocrine cell hyperplasia and appendiceal carcinoids

As endocrine tumours in a number of organs may arise in a background of hyperplasia, the density of endocrine cells in appendices from ten patients with carcinoid tumours was compared with that in appendices from ten age- and sex-matched control patients. Crypt and lamina propria endocrine cells were quantified separately. The density of argentaffin endocrine cells in the crypts was significantly higher in appendices with carcinoid tumours when compared with the controls. No difference was found in non-argentaffin endocrine cells, and no difference was found in either argentaffin or argyrophil endocrine cells in the lamina propria. While it is possible that carcinoid tumours induce an increase in the number of enterochromaffin (EC) cells in the background mucosa, it is considered more likely that EC cell hyperplasia predisposes to the development of carcinoid tumours of the appendix.     

The prevalence, prognostic significance and hormonal content of endocrine cells in gastric cancer

Twenty-six of 100 cases of gastric adenocarcinoma contained argyrophil cells. All these tumours were carcino-embryonic antigen positive and 13 contained variable amounts of gastro-enteropancreatic peptides and amines. There was no significant difference in mucin type, extent or incidence of intestinal metaplasia between tumours with and those without endocrine cells. The prognosis for both groups was similarly poor, contrasting with that for carcinoid and atypical carcinoid. Endocrine cell hyperplasia was evident in the adjacent mucosa in some of the cases of endocrine positive tumours. There was no association between achlorhydria and the presence of endocrine cells in the tumours. The origin of the neoplastic endocrine cells remains speculative, occurring either as a mutation of a single stem cell or as a synchronous malignant transformation of two epithelial cell types exposed to a particular carcinogenic factor(s). Adenocarcinomas containing endocrine cells appear to be as biologically aggressive as the usual adenocarcinomas of the stomach and therefore should be treated in a like manner.     

The morphological characteristics of endocrine-cell cancers of the large intestine

Histological variants of colon carcinoma depending upon the quantity of endocrine cells are distinguished on the basis of 66 malignant epithelial colon tumours morphological investigation. Special emphasis was made on the characteristics of the endocrine cell carcinoma, combined tumours with a combination of glandular and endocrine components, and amphicrin neoplasms. A trabecular-glandular variant of endocrine cell carcinoma is found to be predominant in the colon. The criteria are suggested for the identification of endocrine-cell tumours.     

Differential expression of vesicular monoamine transporter (VMAT) 1 and 2 in gastrointestinal endocrine tumours.

Neuroendocrine tumours are characterized by their capacity to produce hormones, which are stored in vesicles and secretory granules. Demonstration of granule/vesicle proteins in tumours is taken as evidence of neuroendocrine differentiation. Vesicular monoamine transporters (VMAT1 and VMAT2) mediate the transport of amines into vesicles of neurons and endocrine cells. The expression of VMAT1 and VMAT2 and the usefulness of VMAT1 and VMAT2 in the histopathological diagnosis of gastrointestinal endocrine tumours have not been fully explored. This study therefore investigated the expression of VMAT1 and VMAT2 in 211 human gastrointestinal tumours by immunocytochemistry and western blotting. VMAT1 and/or VMAT2 were demonstrated in the majority of amine-producing endocrine tumours of gastric, ileal, and appendiceal origin. Serotonin-producing endocrine tumours (ileal and appendiceal carcinoids) expressed predominantly VMAT1, while histamine-producing endocrine tumours (gastric carcinoids) expressed VMAT2 almost exclusively. In peptide-producing endocrine tumours such as rectal carcinoids and endocrine pancreatic tumours, only a small number of immunopositive tumour cells were observed. No labelling was found in non-endocrine tumours, including gastric, colorectal and pancreatic adenocarcinomas and gastrointestinal stromal tumours. In conclusion, VMAT1 and VMAT2 are differentially expressed by gastrointestinal endocrine tumours, with a pattern specific for each tumour type, reflecting their neuroendocrine differentiation and origin. VMAT1 and VMAT2 may therefore become valuable markers in the classification of neuroendocrine tumours and may also indicate patients suitable for radioisotope treatment operating via these transporter systems.     

Cyclin-dependent kinase (cdk6) and p16 in pancreatic endocrine neoplasms

AIMS: p16 and p27, the inhibitors of cyclin-dependent kinases, have been reportedly decreased in certain human tumours, including a few endocrine tumours. The current study used immunocytochemical staining to compare the staining intensity of cdk6 and its inhibitor, p16, in pancreatic endocrine neoplasms with normal pancreatic islets. METHODS: Twenty-four primary pancreatic endocrine neoplasms, consisting of 12 insulinomas, one glucagomoma, three pancreatic polypeptide (PP)-omas, five gastgrinomas and three non-fuctioning tumours, were immunocytochemically studied for cdk6 and p16 compared with the adjacent non-neoplastic islets. RESULTS: In the normal islets, cdk6 staining was strongly positive for islet cell nuclei and cytoplasms, whereas p16 was strongly positively stained for islet cell cytoplasms. Insulinomas, glucagonoma, PP-omas and non-functioning tumours were weakly stained for cdk6 and p16. Among five gastrinomas, three tumours were moderately stained and two tumours were more weakly stained for cdk6 and p16. Thus, tumour cells were weaker stained for cdk6 and p16 compared with the strong staining of normal islet cells. No distinct immunostaining difference was observed among five kinds of pancreatic endocrine neoplasms. CONCLUSIONS: The decreased immunocytochemical staining for cdk6 and p16 is consistently observed in five kinds of pancreatic endocrine neoplasms. This decreased cdk6 and p16 in pancreatic endocrine neoplasms may be a part of the cell cycle event in tumour transformation and progression, and the same process may involve other endocrine tumours.     

Immunohistochemical and ultrastructural studies on rat islet cell tumours induced by streptozotocin and nicotinamide

Summary Fourteen rat islet tumours induced by Streptozotocin and nicotinamide were examined by light microscopy with indirect immunoperoxidase staining and by electron microscopy. Most tumours consisted predominantly of B cells, but over a half of the tumours examined showed mixed cellularity with considerable numbers of A cells and small numbers of D or PP cells. Only 4 tumours consisted exclusively of B cells. There was no positive reaction for any kind of specific islet hormone antibodies in 2 tumours. Ultrastructurally, most tumours were composed of cells containing numerous secretory granules with B cell properties, with great variation in size, shape and number. We often encountered enterochromaffin-like cells or atypical granular cells or cells containing non-beta secretory granules. We could not identify, however, the ultrastructural counterparts of A or D cells. The results suggested that the multiplicity of the endocrine cells of rat islet cell tumours might be an expression of the cellular dedifferentiation of tumour cells which could re-differentiate into the whole range of components of the endocrine pancreas.Supported by the Scientific Research Grant of the Ministry of Education, Science and Culture, Japan (No. 477190)A part of this study was presented to 68th Congress of Japanese Pathological Society, held in Tokyo, April 1979 and to 10th International Congress of Diabetes, held in Vienna, September 1979The term of gastroentero-pancreatic endocrine cells is used in this report according to the Lausanne classification 1977     

Insulin-like growth factor-II in endocrine pancreatic tumours. Immunohistochemical, biochemical and in situ hybridization findings

In earlier studies a high-molecular-weight (HMW) insulin-like growth factor-II (IGF-II) peptide was identified in adult human pancreas and localized to the insulin-producing B-cells. This peptide has now been investigated in neoplastic insulin cells. Forty endocrine pancreatic tumours and 17 pancreatic adenocarcinomas of ductal type were included in the study. All cases were investigated with immunohistochemical techniques using antibodies to IGF-II, insulin, pro-insulin, glucagon, somatostatin, pancreatic polypeptide, gastrin and vasoactive intestinal peptide (VIP). Frozen tissue from nine tumours and two normal pancreatic glands was extracted, gel separated, and quantified using radioimmunoassay. The tumours were also investigated by in situ hybridization. IGF-II-immunoreactive cells were found in nearly all the 18 insulin-producing tumours (16/18), in a minority of the other endocrine tumours, but not in pancreatic adenocarcinomas. All extracts from the endocrine tumours showed varying amounts of IGF-II and had different molecular-weight forms. The immunohistochemical and radioimmunoassay findings are both based on immunological binding and were further confirmed by Northern blot and in situ hybridization. These results show that IGF-II is expressed in insulin-producing tumours as well as in pancreatic tumours producing other peptides, in contrast to normal pancreatic islets where IGF-II is found exclusively in insulin-producing cells.     

Telomerase activity in pancreatic endocrine tumours: a potential marker for malignancy.

AIMS: Telomerase activation is known to be a common event in human cancer and may be a useful marker for malignancy. In general, the histological features of pancreatic endocrine tumours cannot be used to determine their malignant potential. The aim of this study was to investigate the role of testing telomerase activity in pancreatic endocrine tumours. METHODS: Prospectively collected fresh frozen tissue specimens from 10 patients with pancreatic endocrine tumours (nine insulinomas, one adrenocorticotrophin producing pancreatic endocrine tumour) were examined by a highly sensitive polymerase chain reaction (PCR) based telomerase repeat protocol (TRAP). RESULTS: Of the 10 pancreatic endocrine tumours, three had telomerase activity. The positive cases included two frankly malignant tumours with liver metastases and one pancreatic endocrine tumour occurring in the setting of multiple endocrine neoplasia type 1. The latter had an infiltrative border. Vascular and perineural tumour infiltration was noted. In the two malignant pancreatic endocrine tumours with liver metastases, telomerase activity was noted in the tumour and the adjacent morphologically non-neoplastic pancreas. CONCLUSION: To our knowledge, this is the first report of the role of telomerase activity in pancreatic endocrine tumours. Telomerase activity might be useful for distinguishing between benign and malignant pancreatic endocrine tumours.     

Immunocytochemical demonstration of intermediate filament cytoskeleton proteins in human endocrine tissues and (neuro-) endocrine tumours

Summary The presence and distribution of intermediate filament proteins, such as cytokeratins, vimentin, neurofilament proteins and glial fibrillary acidic protein were assessed immunohistochemically in pituitary adenomas, medullary thyroid carcinomas, endocrine pancreatic tumours, gastric, intestinal and bronchial carcinoids, parathyroid adenomas, pheochromocytomas, paragangliomas and related non-neoplastic tissues. In some cases, immunohistochemical results were correlated with cytoskeletal proteins as analysed by SDS-polyacrylamide gel electrophoresis. Cytokeratin antibodies with broad range of immunoreactivity (i.e. to murine liver cytokeratin component D) reacted with epithelial cells in all non-neoplastic endocrine tissues and related neuroendocrine tumours studied, except for adrenal medulla, pheochromocytoma and paraganglioma, independently of hormone production and biological behaviour. In contrast, antibodies to epidermis-derived cytokeratins failed to stain endocrine tissues and tumours. Paranuclear cytokeratin accumulations were seen in bronchial, gastric, and intestinal carcinoids and seem to be a common feature of neuroendocrine tumours. One-and two-dimensional SDS-polyacrylamide gel electrophoresis of non-neoplastic endocrine tissues and related tumours revealed two major keratin polypeptides corresponding to cytokeratins No. 8 and 18 of the cytokeratin catalog of human cells (Moll et al. 1982). According to this cytokeratin polypeptide composition, endocrine tissues and related tumours conform to the simple type of epithelia. Vimentin-related immunoreactivity was restricted to stromal cells and to folliculo-stellate cells in normal pituitary gland, Schwann cells in carcinoids and satellite cells in normal adrenal medulla and in pheochromocytomas. Neurofilament protein- (70 kD)-antibodies only stained nerve fibers in normal tissues and at the periphery of carcinoid tumour cell complexes, and, to a variable degree, cells in nontumorous adrenal medulla, pheochromocytomas and paragangliomas. Furthermore, neurofilament reactivity was observed along with cytokeratin expression in two bronchial carcinoids.     

Immunohistochemical localization of acidic fibroblast growth factor in normal human enterochromaffin cells and related gastrointestinal tumours

Acidic fibroblast growth factor (aFGF) is a member of the structurally related heparin-binding growth factor family. The best studied members of this family are aFGF and basic FGF (bFGF), which are potent mitogens and differentiation factors for mesodermderived cells, including fibroblasts. This study was designed to verify the immunohistochemical expression of aFGF in normal human endocrine cells of the gut and in related endocrine tumours. We examined normal gastrointestinal mucosa from seven different subjects and 41 gut endocrine tumours from different sites, including stomach, duodenum, and small and large intestine, using an aFGF polyclonal antibody with no cross-reactivity for bFGF. We localized aFGF in a fraction of serotonin-producing enterochromaffin (EC) cells of the normal gut, while it was absent in gastrin (G), CCK, secretin (S), somatostatin (D) and glicentin (L) cells. aFGF immunoreactivity was also expressed in serotonin producing EC cell tumours, but not in other functional types of gut endocrine neoplasms investigated, including gastric ECL cell, duodenal somatostatin and gastrin cell, and rectal L cell tumours. A positive correlation was found between expression of aFGF and the amount of tumour fibrous stroma, suggesting that aFGF may be involved in proliferation and activity of stromal fibroblasts.     

Pancreatic endocrine tumors

Pancreatic endocrine tumours are rare tumours, and arise from the types of pancreatic cells that produce hormones. These tumours may or may not secrete hormones themselves and may or may not be cancerous (malignant). Functioning tumours secrete a particular hormones which may cause various syndromes. The present article reviews the latest reports on the pancreatic endocrine tumours.     

Cystatin C in the human pancreas and gut: An immunohistochemical study of normal and neoplastic tissues

Summary The occurrence of immunoreactive cystatin C (CC) in normal and neoplastic cells of the human pancreas and gut was investigated using an indirect streptavidin-biotin method on formaldehyde-fixed and paraffin-embedded tissues. Virtually all pancreatic islet cells and many neuroendocrine cells throughout the gastrointestinal tract showed strong CC immunoreactivity and a granular cytoplasmic staining pattern. All 14 endocrine pancreatic tumours (insulinomas, glucagonomas, gastrinomas and non-producing tumours), as well as 16 of 17 gut carcinoid tumours, were also strongly CC immunoreactive. In addition, non-endocrine epithelial cells of pancreatic ducts and the gastrointestinal mucosa and 20 of the 24 adenocarcinomas from these sites showed weak CC immunoreactivity. Thus, CC cannot be used as a reliable immunohistochemical marker for endocrine gastro-entero-pancreatic tumours despite the fact that the protein is strongly expressed in a majority of such tumours.     

Detection of apoptosis by the TUNEL technique in clinically localised prostatic cancer before and after combined endocrine therapy.

AIMS: Apoptosis in prostate cancer was evaluated after three months of combined endocrine therapy to investigate the association with tumour grade, tumour stage, and the immunohistochemical detection of p53 and bcl-2 in tumour cells before and after therapy. METHODS: Twenty six formalin fixed, paraffin wax embedded core biopsies and corresponding prostatectomy specimens, excised after three months of combined endocrine therapy, were analysed for the presence of apoptotic cells by the terminal deoxynucleotidyl transferase mediated dUTP-biotin nick end labelling (TUNEL) method, and for p53 and bcl-2 overexpression by immunohistochemistry. RESULTS: All 26 adenocarcinomas were clinically localised at diagnosis. In biopsies performed before combined endocrine therapy, the apoptotic indices varied between 0.09% and 1.73%, while the tumour grade fell between Gleason score 1 and 8. The mean (SD) apoptotic count pretherapy was 0.71% (0.50). There was a significant association between elevated apoptotic counts and higher Gleason scores in the biopsies (p = 0.005). After three months of therapy, the percentage of apoptotic tumour cells increased independently of tumour stage, while a significant association with Gleason grade was found (p = 0.0018) and all the tumours had Gleason scores of < 7. In eight cases the apoptotic index was more than twice its pretherapy value. The remaining tumours showed less of an increase in the apoptotic index (five cases) or a reduction in the percentage of apoptotic cells. The overall moderate increase in apoptotic index after combined endocrine therapy was not statistically significant (p = 0.8). Immunoreactivity to p53 was absent in all cases, before and after therapy, while a slight increase in the number of cells overexpressing bcl-2 was observed in five of the 13 tumours (38.1%) with reduced apoptotic indices after therapy. CONCLUSIONS: After three months of combined endocrine treatment a minority of clinically localised prostate neoplasms showed regressive epithelial alterations, associated with an increase in apoptotic tumour cells; an increase in cells overexpressing bcl-2 was observed in five of the 13 tumours with reduced apoptotic indices.     

Clinico-pathological features of a series of 11 oncocytic endocrine tumours of the pancreas

Oncocytic changes may occur very infrequently in neuroendocrine tumours. To estimate the prevalence, pathological features and clinical behaviour of oncocytic endocrine tumours of the pancreas, we reviewed a series of 227 lesions from two institutions. Eleven cases with predominant oncocytic features were selected, representing 4.85% of the whole series. The morphological features and immunophenotype of such tumours did not differ from conventional endocrine pancreatic tumours, except for the presence of abundant eosinophilic and granular cytoplasm. Anti-mitochondrial antigen was positive in all cases tested, and by electron microscopy, numerous mitochondria were observed in the cytoplasm of tumour cells. The majority of cases were nonfunctioning, and in most cases, pathologic signs of malignancy, leading to a diagnosis of endocrine carcinoma, were observed. In addition, the three nonmalignant cases matched the criteria of well-differentiated tumours of uncertain malignant potential. Nearly 50% of the cases were clinically aggressive, and lymph node and liver metastases were present at the time of diagnosis in a minority of cases. Therefore, oncocytic endocrine pancreatic tumours represent a peculiar morphological and clinical variant characterised by frequent hormonal inactivity and malignant behaviour, which should be considered in the differential diagnosis, especially when dealing with a metastatic lesion.     

Dpc4 is expressed in virtually all primary and metastatic pancreatic endocrine carcinomas

DPC4/Smad4 is inactivated in about 50% of pancreatic ductal cancers. It has been recently reported that this gene is also inactivated in neoplasms arising from pancreatic islet cells, a phenomenon suggested to be related to similar progressions of malignancy found in common ductal cancers. To evaluate this possibility, we analysed 20 metastases of pancreatic endocrine carcinomas and their corresponding primary lesion for inactivation of DPC4 using immunohistochemical staining. In fact, immunohistochemical labelling has been shown to correlate with DPC4 gene status with high sensitivity and specificity. The cancers included 18 nonfunctioning tumours, one gastrinoma and one ViPoma all with liver, nodal and/or adrenal metastases. Seventeen were well-differentiated and three poorly differentiated endocrine carcinomas. Dpc4 expression was absent in only one primary well-differentiated endocrine cancer and its liver metastasis, while all the remaining 19 primary tumours and their metastases stained positive for the protein. All positively staining cases showed diffuse cytoplasmic and nuclear staining in virtually all neoplastic cells. Our data suggest that DPC4 is only rarely involved in pancreatic endocrine tumourigenesis and give further weight to the hypothesis that tumours arising from pancreatic exocrine and endocrine epithelia are genetically distinct.     

Immunocytochemistry and electron microscopy of an argentaffin endocrine tumour of the pancreas

Summary An endocrine pancreatic tumour that had not caused any endocrine symptoms was examined by histological, immunocytochemical and electron microscopic techniques. The majority of the tumour cells were argentaffin and contained secretory granules of the enterochromaffin cell type. Immunocytochemically a minority of tumour cells reacted to antisera against -endorphin, met- and leu-enkephalin, gastrin, somatostatin and ACTH. The tumour was thus multihormonal, and appeared to be more closely related to the classic Carcinoid tumours of the mid-gut than to most pancreatic endocrine tumours.     

Immunohistochemical localization of α- and βA-subunits of inhibin/activin in human normal endocrine cells and related tumors of the digestive system

 Activin A and inhibin A, first isolated from the ovary, are dimeric proteins able to modulate pituitary FSH secretion. Inhibin A is a heterodimer composed of one α-subunit and one βA-subunit (α-βA), while activin A is a homodimer of the βA-subunit (βA-βA). Their identification in several tissues has suggested that they have numerous physiological functions, acting as either paracrine or autocrine factors. The aim of this study was to evaluate the expression of activin A and inhibin A in normal endocrine cells and in 70 endocrine tumours from different sites in the gastro-entero-pancreatic system, using specific monoclonal antibodies directed against the α- and βA-subunits of inhibin/activin. Immunoreactivity for the βA-subunit, but not for the α-subunit, was observed in normal G, EC, and GIP cells of the antrum and duodenum, and in pancreatic A cells. βA-subunit expression was observed in G cell and A cell tumours, and in a few insulinomas and ileal EC cell carcinoids. The α-subunit was found in rare cells in 7 of the 70 tumours and was colocalized with the βA-subunit in only 1 tumor. Specific types of endocrine cells from the gut and pancreas appear to produce only activin A, a possible paracrine or autocrine modulator. Activin A is mainly produced by tumours derived from endocrine cells that normally express it. Received: 17 July 1998 / Accepted: 30 July 1998     

Two distinct types of islet abnormalities associated with endocrine pancreatic tumours

Summary Morphological and immunocytochemical studies of pancreatic material from eighteen patients with endocrine pancreatic tumours revealed two distinct types of islet abnormalities, both of which were associated with neoformation of endocrine cells from duct epithelium. Due to this phenomenon and the occurrence of greatly increased numbers of certain endocrine cell types the abnormalities were tentatively classified as hyperplasias. Hyperplasia type I was characterized by increases in number of all islet cell types. Increments in numbers of insulin and glucagon cells were most important quantitatively. Neoformation of islet cells from ducts (nesidioblastosis) was especially conspicuous with this type of hyperplasia. To some extent the islet cell neoformation resembled that seen in the human fetal pancreas. Hyperplasia type I was found in addition in two patients having hypergastrinemia due to achlorhydria. It is suggested that this type of abnormality results from a stimulatory effect of gastrin on the formation of pancreatic islet cells. Endocrine pancreatic tumours other than Zollinger-Ellison tumours were frequently, but not invariably, associated with hyperplasia type II, characterized by striking increases in frequency (and conceivably total mass) of pancreatic polypeptide (PP) cells. The variable occurrence of hyperplasia type II could not be related to any specific clinical abnormality. It seems possible that this hyperplasia may represent a non-specific response to pancreatic injury.     

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.The work reported in this paper was supported by grants from the Italian Association for Cancer Research (AIRC; C.B.) and from the Italian Ministry for University and Scientific and Technological Research (MURST; M.B., L.U., C.C.)     

Glandular duodenal carcinoid--a somatostatin rich tumour with neuroendocrine associations

The clinical and pathological features of four cases of duodenal carcinoid tumour are presented. All four tumours showed a glandular pattern, and in three cases this was associated with psammoma bodies. In three tumours somatostatin was identified by immunocytochemistry in most tumour cells. In two cases the duodenal tumours were associated with von Recklinghausen's disease and phaeochromocytoma. The importance of these unusual features is discussed, and it is suggested that these glandular carcinoids are a specific subgroup of endocrine cell tumours which appear to have potentially important clinical and pathological associations.