Argentaffin cell adenocarcinoma of the stomach: an atypical carcinoid?

Towards Understanding of Gastric Cancer Based upon Physiological Role of Gastrin and ECL Cells

Simple Summary

Generally, we know that cancers represent genetic changes in tumour cells, but we most often do not know the causes of cancers or how they develop. Our knowledge of the regulation of gastric acid secretion is well known, with the gastric hormone gastrin maintaining gastric acidity by stimulation of the enterochromaffin-like (ECL) cell to release histamine, which subsequently augments acid secretion. Furthermore, it seems to be a general principle that stimulation of function (which, for the ECL cell, is release of histamine) in a parallel way stimulates the proliferation of the same cell. Long-term hyperstimulation of cell division predisposes to genetic changes and, thus, development of tumours. All conditions with reduced gastric acidity result in an increased risk of gastric tumours due to elevated gastrin in order to restore gastric acidity. It is probable that Helicobacter pylori infection (the most important cause of gastric cancer), as well as drugs inhibiting gastric acid secretion induce gastric cancer in the long-term, due to an elevation of gastrin caused by reduced gastric acidity. Gastric carcinomas have been shown to express ECL cell markers, further strengthening this relationship.

Abstract

The stomach is an ideal organ to study because the gastric juice kills most of the swallowed microbes and, thus, creates rather similar milieu among individuals. Combined with a rather easy access to gastric juice, gastric physiology was among the first areas to be studied. During the last century, a rather complete understanding of the regulation of gastric acidity was obtained, establishing the central role of gastrin and the histamine producing enterochromaffin-like (ECL) cell. Similarly, the close connection between regulation of function and proliferation became evident, and, furthermore, that chronic overstimulation of a cell with the ability to proliferate, results in tumour formation. The ECL cell has long been acknowledged to give rise to neuroendocrine tumours (NETs), but not to play any role in carcinogenesis of gastric adenocarcinomas. However, when examining human gastric adenocarcinomas with the best methods presently available (immunohistochemistry with increased sensitivity and in-situ hybridization), it became clear that many of these cancers expressed neuroendocrine markers, suggesting that some of these tumours were of neuroendocrine, and more specifically, ECL cell origin. Thus, the ECL cell and its main regulator, gastrin, are central in human gastric carcinogenesis, which make new possibilities in prevention, prophylaxis, and treatment of this cancer.

Gastric and duodenal neuroendocrine tumours

Gastric neuroendocrine neoplasms (NENs) are increasing in frequency and have a varied spectrum with regard to histology, clinicopathologic background, stage, and prognosis. They are usually discovered incidentally, are for the most part benign and are associated with hypergastrinaemia (secondary either to chronic atrophic gastritis or rarely Zollinger-Ellison syndrome; types 1 and 2, respectively) or more rarely sporadic type 3. Applications of recent staging and grading systems - namely using Ki-67 proliferative indices - (from ENETS and WHO 2010) can be particularly helpful in further categorising these tumours. The natural history of Type 1 gastric carcinoids is generally (>95%) favourable and simple surveillance is usually recommended for small (<1 cm) T1 tumours, with local (endoscopic or surgical) resection for larger lesions. Other potential therapies such as somatostatin analogues and gastrin receptor antagonists may offer newer therapeutic possibilities. Rarely, gastric NENs have a malignant course and this is usually confined to Type 2 and especially Type 3 tumours; the latter mimic the biological course of gastric adenocarcinoma and require radical oncological therapies. Most duodenal NENs, apart from gastrinomas (that are not dealt with here) are sporadic and non functional. They are also increasing in frequency probably due to incidental discovery at endoscopy or imaging for other reasons and this may account for their overall good prognosis. Peri-ampullary and ampullary NENs may have a more aggressive outcome and should be carefully appraised and treated (often with surgical resection).

Mixed Adenoneuroendocrine Carcinomas (MANECs) of the Gastrointestinal Tract: An Update

The systematic application of immunohistochemical techniques to the study of tumors has led to the recognition that neuroendocrine cells occur rather frequently in exocrine neoplasms of the gut. It is now well known that there is a wide spectrum of combinations of exocrine and neuroendocrine components, ranging from adenomas or carcinomas with interspersed neuroendocrine cells at one extreme to classical neuroendocrine tumors with a focal exocrine component at the other. In addition, both exocrine and neuroendocrine components can have different morphological features ranging, for the former, from adenomas to adenocarcinomas with different degrees of differentiation and, for the latter, from well differentiated to poorly differentiated neuroendocrine tumors. However, although this range of combinations of neuroendocrine and exocrine components is frequently observed in routine practice, mixed exocrine-neuroendocrine carcinomas, now renamed as mixed adenoneuroendocrine carcinomas (MANECs), are rare; these are, by definition, neoplasms in which each component represents at least 30% of the lesion. Gastrointestinal MANECs can be stratified in different prognostic categories according to the grade of malignancy of each component. The present paper is an overview of the main clinicopathological, morphological, immunohistochemical and molecular features of this specific rare tumor type.

Goblet cell carcinoids at extraappendiceal locations of gastrointestinal tract: an underrecognized diagnostic pitfall

BACKGROUND

Goblet cell carcinoid (GCC) is a clinicopathologically distinctive tumor that typically arises in appendix and metastasizes frequently. Although rare cases of ostensibly primary extraappendiceal GCC (EGCC) have been reported, the distinction from extraappendiceal metastasis of occult appendiceal primary may be problematic and has not been dealt with systematically in literature.

METHODS

We reviewed our combined experience with EGCC at four North American hospitals and reevaluated all EGCC cases published in literature.

RESULTS

We encountered 16 cases that were initially reported as EGCC. Five cases presented with disseminated abdominopelvic spread, nine cases with mass lesions in stomach, ileum, cecum, ascending colon, hepatic flexure, sigmoid, and rectum. One case was found incidentally in an ascending colon adenomatous polyp. A negative appendix was confirmed in 2 (12.5%) cases, whereas a primary appendiceal GCC was discovered in 4 (25%) cases at a later date, and appendix was not available for review in 10 cases (62.5%). Of 10 cases of EGCC found in literature, the tumor sites included stomach, duodenum, jejunum, ileum, cecum, splenic flexure, and rectum. Primary appendiceal tumor was excluded histologically in one (10%), grossly in three (30%), and not at all in six (60%). Nine of our cases were initially misdiagnosed as signet-ring cell adenocarcinomas.

CONCLUSIONS

True EGCC is extremely rare. GCC found at locations other than appendix are most likely extraappendiceal presentations of appendiceal primary. A thorough review of the pathologic status of appendix should be a mandatory diagnostic criterion and should always be documented in the pathology reports.

Classification of tumours

Tumours are classified according to the most differentiated cells with the exception of carcinomas where a few tumour cells show neuroendocrine differentiation. In this case these cells are regarded as redifferentiated tumour cells, and the tumour is not classified as neuroendocrine. However, it is now clear that normal neuroendocrine cells can divide, and that continuous stimulation of such cells results in tumour formation, which during time becomes increasingly malignant. To understand tumourigenesis, it is of utmost importance to recognize the cell of origin of the tumour since knowledge of the growth regulation of that cell may give information about development and thus possible prevention and prophylaxis of the tumour. It may also have implications for the treatment. The successful treatment of gastrointestinal stromal tumours by a tyrosine kinase inhibitor is an example of the importance of a correct cellular classification of a tumour. In the future tumours should not just be classified as for instance adenocarcinomas of an organ, but more precisely as a carcinoma originating from a certain cell type of that organ.

Histological and immunohistochemical study of composite neuroendocrine-exocrine carcinomas of the stomach

Composite neuroendocrine-exocrine carcinomas (NEECs) with two distinct components of adenocarcinoma and neuroendocrine (NE) carcinoma within the same tumor are rare but may have a clue for clarifying the pathogenesis of NE tumors arising from non-endocrine organs. This study was done to characterize histological and immunohistochemical features of NEECs of the stomach comparing with pure NE tumors of the gastrointestinal (GI) tract. Microscopically, adenocarcinoma components in 6 of 8 NEECs were well differentiated and located superficially, whereas NE components were poorly differentiated and located deeply. In the remaining two cases, smaller NE components were intermingled within adenocarcinoma components. Immunohistochemically, neural cell adhesion molecule (NCAM) was positive in 5 NE components, of which 3 cases were homogeneously positive, and 2 adenocarcinoma components of 8 NEECs, while 19 of 21 pure NE tumors of GI tract were homogeneously positive for NCAM. Ghrelin-immunoreactivity was found in 4 NE components and 2 adenocarcinoma components of NEECs, although 20 pure NE tumors were positive for ghrelin. Smad4 was positive in both components of 7 NEECs. These findings suggest that composite NEECs and pure NE tumors of GI tract may have different NE properties and that most NE components of composite NEECs of the stomach may originate from an adenocarcinoma precursor cell and occasional tumors from a pluripotent cell.

Endocrinocarcinomas (carcinoids and their variants) of the duodenum. An evaluation of 927 cases

This study was undertaken to supplement our previous analysis of 635 duodenal carcinoids to give both wider and different viewpoints on a larger series of duodenal endocrinocarcinomas, and to provide up-to-date clinicopathologic information regarding these neoplasms. A total of 927 cases of such neoplasms of the duodenum were collected from the Niigata Registry for gut-pancreatic endocrinomas, consisting of the carcinoid group with 897 cases, 857 typical carcinoids and 40 atypical varieties, and the variant group with 30 remaining endocrinocarcinomas expressed by various terminology. Significant statistical differences between these two groups were evident in various aspects: in sites of tumor growth, aggressiveness of invasion to the extra-duodenal structures, rates and sites (liver, lymph nodes and bone) of metastases, average tumor-size, immunohistochemistry of gastrin and serotonin, rates of recurrence, five-year survival rates and others. In addition, a close similarity between these two groups was noted in several aspects of histology, histochemistry and immunohistochemistry, rendering the variant group in a member of the carcinoid family. Regarding the carcinoid group in comparison with that in other organs may be summarized as follows: a reasonable male/female ratio of 1.39, a reasonable average age of 55.9 years, a high typical/atypical ratio of 21.4, a relatively small average tumor-size of 17.7 mm, a relatively low metastasis rate of 27.4%, a high histologic B-type dominance of 75.5%, a high postoperative survival rate of 83.3% and a reasonable incidence of the carcinoid syndrome of 3.1%.

Ductal and acinar differentiation in pancreatic endocrine tumors

Rare pancreatic endocrine tumors consisting of both exocrine and endocrine components have been reported sporadically. We investigated the ductal and acinar differentiation in pancreatic endocrine tumors. In immunohistochemical studies of 28 pancreatic endocrine tumors, staining with anti-carcinoembryonic antigen (CEA) or CA19-9 antibody indicated ductal differentiation, while staining with anti-amylase or anti-trypsin antibody indicated acinar differentiation. K-ras gene mutations and p53 gene alterations also were studied. Ten tumors were immunoreactive for CEA or CA19-9. Five tumors diffusely immunoreactive for CEA or CA19-9, in addition to endocrine markers, were diagnosed as duct-endocrine cell tumors of the pancreas. Two tumors diffusely immunoreactive for CEA or CA19-9 and also for pancreaticogut hormones as well as endocrine markers were diagnosed as duct-acinarendocrine cell tumors. These tumors showed uniform histologic features and synchronous ductal, acinar, and endocrine differentiation, distinct from the coexisting different cellular populations seen in collision tumors. All tumors were malignant. These duct-endocrine cell tumors or duct-acinar- endocrine cell tumors of the pancreas may be derived from a stem cell that retains the capability of expressing either an exocrine or endocrine phenotype. Only one K-ras gene mutation and no p53 gene alterations were detected in these tumors, which suggests that they constitute an entity with a different origin than ductal carcinomas.

Goblet cell carcinoid arising in a mature teratoma of the mediastinum

Goblet cell carcinoid (GCC) is a rare but distinctive neoplasm with features of both adenocarcinoma and carcinoid tumor. Most cases described in the literature have occurred in the appendix. An additional well-defined location is the ovary, and these tumors have been associated with a mature teratoma of the ovary. GCC arising within a mature teratoma of the mediastinum has not been described in the English-language literature. We report a case of this previously undescribed entity and provide a review of the literature on mediastinal teratomas with malignant transformation. The histologic findings included uniform, smooth-bordered glandular nests lined by goblet cells and admixed endocrine and Paneth cells. Occasional tubular glands were present, as were transitional type glands with both goblet cell and tubular features. Cytologic atypia was minimal, and mitotic activity was rare. Immunohistochemical studies showed positive staining of GCC tumor cells with chromogranin, cytokeratin, neuron-specific enolase, serotonin (focal), and Leu-7 (focal). The GCC component was entirely contained within the mature teratoma.

Carcinomas of the colon with multidirectional differentiation. Report of two cases and review of the literature

Two cases of colonic carcinomas with multidirectional differentiation are presented. Both tumors showed light microscopic and immunohistochemical evidence of areas of adenocarcinomatous, squamous cell carcinomatous, and neuroendocrine differentiation. Only six similar cases have been previously reported. These highly malignant tumors support the recent concept of a multipotential stem cell within the mucosa of the gastrointestinal tract capable of differentiation in several directions.

Neoplastic argentaffin cells with intracytoplasmic eosinophilic granules in a gastric adenocarcinoma

A case of poorly differentiated adenocarcinoma of the stomach with unique histological features is reported: in addition to characteristic adenocarcinoma cells, a large number of tumor cells contained bright eosinophilic and argentaffin granules in their cytoplasm. On routine histologic examination, the latter cells closely resembled the endocrine cells present in the normal human gastrointestinal tract, although the granules were distributed throughout the cytoplasm and did not show any polarity, which is usually subnuclear in normal endocrine cells. Immunohistochemical studies demonstrated positive staining for lysozyme, CEA, gastrin and HCG. Electron microscopic examination revealed cytoplasmic neurosecretory granules, and some tumor cells were found to contain both secretory granules and mucinous material within the same cytoplasm. These neoplastic endocrine cells presumably originated from primitive digestive system elements capable of differentiating towards both endocrine and mucus-secreting varieties.

Small-cell carcinoma of gallbladder. An immunocytochemical and ultrastructural study

An unusual carcinoma of the gallbladder in a seventy-one-year-old woman displayed features of a well-differentiated adenocarcinoma, atypical carcinoid and small cell undifferentiated carcinoma. The patient died from progressive hepatic failure four months after surgery. Autopsy showed bulky liver masses and several peritoneal nodules exclusively composed of small, hyperchromatic cells. The neuroendocrine nature of the small cell component of the tumor was documented by the presence of neurosecretory granules at the ultrastructural level and by immunocytochemical positivity to NSE and Synaptophysin. The epithelial markers, cytokeratin and CEA, were also positive in the carcinoid and in the undifferentiated portions of the tumor. A common endodermal origin is suggested for carcinoid and small cell carcinoma of the gallbladder.

A case of coexisting malignant carcinoid tumor and adenocarcinoma in the papilla of Vater

A 47-year-old Japanese woman in whom obstructive jaundice had already been diagnosed, was found to have a dome-shaped elevated tumor approximately 3 cm in diameter located in the area very close to the papilla of Vater on endoscopical and radiographical investigations. Histopathologically, the resected tumor was composed mainly of solid nests of atypical argyrophilic cells, and partially of an area of well differentiated tubular adenocarcinoma, showing mutual transition in the mucosal layer. Both immunohistochemical and ultrastructural analyses confirmed the difference in character of tumor cells between these two areas: neuroendocrine cell carcinoma and tubular adenocarcinoma of common type in the intestine. To the best of our knowledge, this is only the third case reported to be a coexisting malignant carcinoid tumor and adenocarcinoma arising in the periampullary region.

Composite (adenocarcinoid) tumors of the gastrointestinal tract

Tumors of the gut with composite features of both adenocarcinoma and carcinoid have been recognized mainly in the appendix. There also have been isolated reports of similar tumors arising from other parts of the gastrointestinal tract. It is generally concluded that these tumors have better prognosis than adenocarcinomas of the gastrointestinal tract. We reported six patients with composite tumors arising from the stomach in one, small intestine in two, cecum in two, and rectum in one patient. Clinical presentations in each was suggestive of malignancy with extension to either serosa and/or lymph nodes. Metastasis to liver was present in two patients. Histologically, the tumor showed glands with surface microvilli resembling adenocarcinoma and also organoid pattern with neurosecretory granules in cells resembling carcinoid. Two patients died three and nine months after surgery. The clinical presentation, findings at operation, and the postsurgical course of these six patients reveal that these tumors behave more like an adenocarcinoma than carcinoid and do not appear to have a better prognosis than ordinary adenocarcinoma.

Atrophic gastritis and gastric carcinoid tumours

During recent decades an increasing number of case reports have pointed at a relation between atrophic gastritis type A and gastric carcinoid. This relation has now been quantitatively documented in endoscopic screening studies. Among patients with pernicious anaemia the prevalence of gastric carcinoid was 2-9%. Many of these carcinoids, however, remain subclinical. The majority are broadbased polypoid tumours. Most are situated in the gastric body or fundus. Of 95 patients with atrophic gastritis and gastric carcinoid reported in the literature, 60 (63%) had multicentric tumours and 13 (14%) lymph node and/or hepatic metastases. Microscopically, the tumours, which are frequently of the enterochromaffin-like cell type, show various structural differentiations, glandular differentiation indicating malignant potential. Purely intramucosal carcinoids have been described. The precurser lesion to such "early carcinoids", as well as to infiltrating carcinoids, is probably hyperplasia of endocrine cells in the atrophic fundic mucosa. Such hyperplasias, whether nodular or diffuse, are quantitatively related to hypergastrinaemia, which is a typical feature of antrum sparing (type A) atrophic gastritis. Most tumours can be treated endoscopically, although antrectomy with abolition of hypergastrinemia may be the definitive treatment. It seems that the risk of developing gastric carcinoid 'per se' does not justify regular gastric screening in patients with type A atrophic gastritis. However, as these patients also run an increased risk of developing several benign diseases, gastric adenocarcinoma, and probably also pancreatic malignancy, regular survey in selected cases is indicated.

Neuroendocrine tumors of the gastrointestinal tract

Neoplastic proliferations of neuroendocrine cells (NE) may occur throughout the entire GI tract but affect particularly appendix and ileum ("midgut carcinoids"), rectum ("hindgut carcinoids"), as well as stomach and the duodenum ("foregut carcinoids"). Only more exceptionally, they arise in the esophagus, jejunum and colon. The NE tumors encompass a heterogeneous gross and microscopic structural spectrum, ranging from inconspicuous microproliferations ("mucous membrane nevi") to bulky tumor masses. Their growth patterns are usually characteristic and easily recognized. In doubtful cases their NE differentiation becomes established by a characteristic silver affinity, by the ultrastructurally observed presence of characteristic "endocrine" secretion granules, and by immunohistochemically detectable occurrence of "pan-NE markers" (neuron-specific enolase, chromogranins, and synaptophysin), biogenic amines (mainly serotonin), and neurohormonal peptides. Foregut carcinoids usually contain serotonin, gastrin, and somatostatin, midgut carcinoids often only serotonin and tachykinins, whereas the hindgut carcinoids as a rule are multihormonal with a wide spectrum of hormonal peptides, including even insulin. Most GI NE tumors are found in the appendix (50%) and the ileum (30%). Practically all (98%) of the appendiceal NE tumors are benign. They have recently been proposed as arising from apparently Schwann-cell-related NE cells in the submucosa, whereas the ileal--and probably also all the other non-appendiceal NE tumors--are derived from the totipotential cells in epithelial crypts of the mucosa. Among the ileal NE neoplasms a large number can metastasize and result in a fatal outcome. The ability to metastasize is related to the size and to the multiplicity of the primary tumors at the time of initial diagnosis and, to some extent, to their histopathologic growth pattern. Now, some relationship between the prognosis and the cytochemically assessed nuclear DNA content of the NE tumor cells has also been established; not less than about 1/4 to 1/3 seem to be aneuploid. Almost 90% of the rectal carcinoids are benign. Exceptionally, a highly malignant NE neoplasms can arise from the colon/rectum--as well as from the esophagus--composed of NE cells of small and intermediate size. The NE tumors of the stomach are often composed of ECL (enterochromaffin-cell-like) cells; such ECL cell carcinoids are related to atrophic gastritis with pernicious anemia; experimentally, they can be induced by hypergastrinemia in rats. Duodenal carcinoids often contain psammoma bodies and can be associated with neurofibromatosis.

Gastric carcinoid tumors, endocrine cell hyperplasia, and associated intestinal metaplasia. Histologic, histochemical, and immunohistochemical findings

Eleven cases of gastric carcinoid tumor have been studied to review their clinical and pathologic spectrum, to identify any relationship to pernicious anemia, and to evaluate the accompanying gastric mucosal changes, with particular reference to the endocrine cell population. Seven patients were male and four female; ages ranged from 26 to 83 years. Two male patients had documented pernicious anemia and one female patient had unconfirmed pernicious anemia. All patients had marked gastric intestinal metaplasia (atrophic gastritis), which was predominantly fundal (Type A) in three patients with suspected/proven pernicious anemia and antral (Type B) in the other eight. In seven patients, the tumors were typical carcinoids, whereas in 4 patients the carcinoids were "atypical"; one carcinoid was completely polypoid. All cases were argyrophilic, and focal mucin positivity was present in four. Focal somatostatin immunoreactivity was present in four cases, serotonin in three cases, vasoactive intestinal polypeptide (VIP) in two cases, and gastrin (G) in one case. Endocrine cell hyperplasia was identified in the gastric mucosa of eight of 11 patients, including all cases with pernicious anemia; in three of eight cases, G-cell hyperplasia was evident. Numbers of serotonin-positive cells were increased in areas of intestinal metaplasia in all cases. In two patients, there was marked endocrine-cell hyperplasia with multiple small carcinoid tumorlets; the tumorlets stained for G in one. Gastric intestinal metaplasia includes intestinal-like endocrine cells. An association exists between atrophic gastritis and gastric carcinoids, and there is a histogenetic link between atrophic gastritis and some cases of gastric carcinoid tumor.

Neoplastic nature of argyrophil cells in urachal adenocarcinoma

The histological, histochemical and electron microscopic features of the metastatic tumors of an urachal adenocarcinoma, were presented. Metastatic tumor nodules in the lungs and brain as well as the primary tumor showed tubular adenocarcinoma containing many argyrophil cells. Immunoperoxidase examination revealed three kind of endocrine cells which contained different endocrine hormones. Electron microscopic examination showed small, round endocrine granules in the endocrine cells and desmosome-like complexes in between these cells and the adjacent glandular neoplastic cells. These findings suggested that the endocrine cells were neoplastic in nature and originated from primitive neoplastic cells as well as glandular neoplastic cells.

Primary mucinous carcinoid tumor of the ovary

A case of primary mucinous carcinoid tumor of the ovary occurring in a 37-year-old woman is described. The tumor, which replaced the left ovary, was accompanied by metastases in the contralateral ovary and para-aortic lymph nodes. Careful investigations excluded metastatic origin of the tumor. The tumor was solid, but contained an epidermoid cyst. There were no other teratomatous elements. The patient was treated with combination chemotherapy. A second-look operation 9 months following diagnosis revealed extensive microscopic involvement of the peritoneal cavity. The patient's condition deteriorated and she died 1 year after diagnosis. Detailed autopsy revealed peritoneal, pleural, lymphatic, and bone marrow carcinomatosis, but no evidence of a primary tumor elsewhere. Microscopic, ultrastructural, and immunocytochemical findings are described. It is considered that primary mucinous carcinoid tumor of the ovary represents a specific histopathologic entity. Unlike other types of primary ovarian carcinoid tumors, it behaves as an aggressive malignant neoplasm.

Gastric endocrine cell hyperplasia and carcinoid tumors in pernicious anemia

Endoscopic screening in 123 patients with pernicious anemia (PA) yielded 4 patients with solitary and 1 patient with multiple gastric carcinoid tumors. Quantitative histologic studies of multiple standardized biopsy specimens showed a significantly increased number of fundic mucosal argyrophil endocrine cells in 40 patients with PA when compared with 15 patients with simple fundic atrophic gastritis (p = 0.002) or 8 normal controls (p = 0.0001). Patients with simple atrophic gastritis had increased numbers of fundic mucosal argyrophil cells as compared with normal controls (p = 0.02). A significant difference was also noticed in the number of antral mucosal argyrophil cells between patients with PA and normal controls (p = 0.01), but not between patients with PA and patients with simple atrophic gastritis. It is concluded that, in addition to having hyperplasia of gastric mucosal argyrophil endocrine cells, patients with PA run an increased risk of developing gastric argyrophil cell carcinoid tumors, which should be regarded as potentially malignant.

Bronchial adenocarcinoid tumor metastatic to skin

A pulmonary neoplasm, evident initially as a metastatic nonpruritic skin rash in a 51-year-old man, progressed during a period of four months, leading to the patient's death. Histologic and histochemical studies of the skin metastasis, which were confirmed by transbronchial biopsy, demonstrated an adenocarcinoid tumor. Further ultrastructural studies of the skin metastasis showed that many tumor cells contained neurosecretory granules, although histochemical analyses had revealed the presence of only a few such tumor cells. Furthermore, in some cells both mucin and neurosecretory granules were present in the cytoplasm, confirming a previous observation in normal human segmental bronchi. These findings support the endodermal origin of such neoplasms.

Histopathological and immunohistochemical study of neuroendocrine tumors of the rectum

A clinicopathological and immunohistochemical study was carried out on 32 cases of neuroendocrine tumors of the rectum. Typical carcinoids consisted of 27 cases, histologically showing uniform round to columnar cells forming solid alveolar nests and ribbon-like or trabecular arrangement. Neuroendocrine carcinomas consisted of 5 cases in which tumor cells with prominent nuclear atypism were arranged in a ribbon-like or trabecular fashion and formed gland-like structures. There were also small round tumor cells resembling lymphocytes. The prognosis of neuroendocrine carcinomas is very poor with marked tumor invasion of lymphatics and veins resulting in liver metastases and death within one year after operation. Thirty cases out of the 32 showed a positive argyrophil reaction, while immunohistochemistry of 29 cases revealed more than one peptide hormone in 23 cases. The most common hormone was somatostatin being present in 18 of the 23 tumors and glucagon in 16 of the 23 tumors. Gastrin/CCK and calcitonin were proven in 6 of the 23 tumors and in 4 of the 23 tumors, respectively. On the other hand, more than two hormones was present in 15 of the 23 tumors examined. Histologically, neuroendocrine tumors have a very wide spectrum. Histogenetically, typical carcinoids and neuroendocrine carcinomas are considered to be of the same origin with the former showing morphological and functional differentiation to endocrine cells and the latter being more undifferentiated.

Composite gastric carcinoid and adenocarcinoma

The light microscopical, histochemical and ultrastructural features of an unusual gastric tumour are presented. Microscopically, the neoplasm showed the features of both a conventional carcinoid tumour and of a mucin-producing adenocarcinoma. The ultrastructural demonstration of individual cells containing both endocrine granules and mucin globules supports the view that gastric enterochromaffin cells are of endodermal origin.

Tumors of the diffuse endocrine system, histochemical and electron-optic aids, and pitfalls in diagnosis

Tumors of the Diffuse Endocrine System are a heterogeneous group of malignant neoplasms which have rather characteristic light microscopic and cytologic features. These are, however, not diagnostic and their identification with separation from non-neuroendocrine carcinomas require important adjunctive evaluations including histochemical analysis, immunocytochemical characterization and electron-optic identification of endocrine secretory products and paracrine effects in the cytoplasm of the neoplastic cells. The importance of proper classification cannot be over-emphasized because of the often considerable biologic and prognostic differences between neuroendocrine carcinomas and other types of carcinoma, notably metastatic carcinomas from the breast and the prostate. Furthermore, the separation of these lesions into two groups; a small cell type and those with large cells (carcinoid type) appears to have clinical significance in both diagnosis and response to therapy.

Gastric carcinoid (gastrinoma) associated with achlorhydria (pernicious anemia)

This report presents a case of multicentric gastric carcinoid (gastrin containing) tumors of the fundus associated with achlorhydria and pernicious anemia. It is suggested that stimulation of the antral G cells and possibly fundic argyrophilic cells by achlorhydria associated with atrophic gastritis may lead to hyperplasia, and eventually to neoplasia in the latter, in the form of gastric carcinoid with gastrin production.

Carcinoid tumor of the gallbladder associated with adenocarcinoma

A case of carcinoid tumor of the gallbladder associated with adenocarcinoma in a 56-year-old man is reported and a review of the literature is made. The tumor was a polypoid mass with a size of 5.5 X 4.0 X 2.8 cm. Histologically, the tumor showed carcinoid and adenocarcinoma with areas of mucous change. Tumor cells containing argyrophil granules were observed in both carcinoidal and adenocarcinomatous areas, but no argentaffin granules were detected in either of the neoplastic areas. Some of the tumor cells had both argyrophil granules and mucin in the same cytoplasm. The electron microscopic study revealed several tumor cells containing neurosecretory granules; however, no clinical signs of hormonal activities of the tumor were observed. The patient died of generalized bone metastases 16 months after surgery. This appears to be the second case of composite tumor of the gallbladder.

Solid carcinomas of the stomach. A combined histochemical, light and electron microscopic study

Twenty cases of solid carcinoma of the stomach (SCS) were studied light and electron microscopically and histochemically. On the histologic, histochemical, and ultrastructural bases they were divided into three subgroups: mucin-secreting carcinomas (MSC) (12 cases); neuroendocrine tumors (NET) (five cases); and composite tumors (CT) (three cases). Histochemically, mucin was detectable at high intensity in most cases of MSC and ultrastructurally, the mucin granules, the number of which varied considerably from cell to cell, showed prominent pleomorphism with varying degree of maturity. Uniformly round neuroendocrine granules were demonstrable in all of the NET cases and in two cases of CT. The argyrophilic stain was negative in two cases of NET, whereas it was positive in three cases of MSC. Thus, there was a discrepancy between the silver nitrate reduction intensity and the ultrastructural demonstrability of neuroendocrine granules. Histologically, combined occurrence of some nuclear palisading of basal cells and rosette-like arrangement without evident glandular formation was specific to NET and this provides a helpful basis for the light microscopic differentiation of this tumor from other type tumors.

A colonic adenocarcinoma with argentaffin cells. An immunoperoxidase study demonstrating the presence of numerous neuroendocrine products

A well-differentiated colonic adenocarcinoma containing large numbers of gastrointestinal neuroendocrine cells is presented. The presence of neurosecretory granules was confirmed by electron microscopy. Immunocytochemistry showed large numbers of serotonin-containing tumor cells and lesser numbers of somatostatin, gastrin, motilin, secretin and neurotensin-containing cells. Some of these hormones are not normally present in the colon in significant numbers of cells. The presence of several cell types within a single tumor supports the concept that the normal epithelial cells of the gastrointestinal mucosa are derived from a common endodermal stem cell. There exists a spectrum of tumors ranging from the classical adenocarcinoma to the classical carcinoid, and this report identifies the position of this case within that spectrum.

Ultrastructural characteristics of duodenal somatostatinomas. II. Granules and vesicles

Ultrastructural findings of granules and vesicles appearing in tumor cells of somatostatinoma are reported. Except for D granules, one granule and four kinds of vesicles were discerned. Some tumor cells had granules of the exocrine type which were similar to those of the chief cells of the stomach. Very small clear vesicles (YO and KO) had accumulated mainly in the apical region of the somatostatinoma cells. Both vesicles were round, unit-membrane bounded and clear in the center, each measuring about 90 and 30 nm in diameter. The cored vesicles normally seen in the sympathetic system were revealed. Doughnut vesicles characterized by double contour membranes were detected together with the cored vesicles. A mixture of exocrine cells of the chief cell-type in the paraneuroma has not been previously reported. And we have as yet very little information as to the doughnut vesicle.

Argyrophilic cell hyperplasia and an atypical carcinoid tumor in chronic ulcerative colitis

An unusual case of chronic ulcerative colitis, is presented in which an atypical carcinoid tumor was seen. Many areas of the mucosa showed glandular changes of chronic injury and dysplasia, and in these areas, argyrophilic cell hyperplasia was identified. Data is presented describing the evolution of argyrophilic cell hyperplasia as a reaction to injury, the evolution of carcinoid tumors in argyrophilic cell hyperplasia, and the relationship of the proliferating argyrophilic cells to the proliferating glandular cells in ulcerative colitis.

Gastric carcinoma with argyrophilic cells: light microscopic, electron microscopic, and immunochemical study

An immunochemical study of a gastric adenocarcinoma with argyrophilic cells showed two areas of tumor that react differently with the usual histochemical reagents as well as with immune sera against gastrin and mucoprotein associated with antigens. Ninety per cent of the tumor cells were PAS positive and contained M2 antigen, and some also contained M1 antigen. About 30 per cent of the M2-positive cells stained strongly with an antigastrin serum as well as with the argyrophilic reagents. The remaining 10 per cent of tumor cells were signet-ring cells located in several clumps in the tumor. These cells were positive for both PAS and alcian blue and contained intestinal M3 antigen. Forty-five per cent of them also contained M1 gastric antigens. Carcinoembryonic antigen (CEA) was found in the cytoplasm of each tumor cell. The presence of CEA and M1 antigen together indicates a fetal pattern, suggesting that the cells originate from very immature gastrointestinal stem cells.

Argyrophil cells in early gastric carcinoma: an immunohistochemical and ultrastructural study

Eighteen argyrophil cell carcinomas in 101 early gastric carcinomas were explained histologically, ultrastructurally, and immunohistochemically for polypeptides, carcinoembryonic antigen (CEA), lysozyme, and human chorionic gonadotrophin (hCG). Seven of these 18 tumors had gastrin, and two of seven tumors also contained somatostatin. In all of these 18 tumors CEA were demonstrated. Seven had lysozyme and five of seven tumors also contained gastrin; hCG were present in four of the 18 tumors and two of four tumors had gastrin, CA, mucin, and lysozyme simultaneously. Argentaffin cells were found in seven of 18 tumors. Of the above seven tumors containing gastrin, three had argentaffin cells. Ultrastructurally, several types of secretory granules were noted and tumor cells resembling D1- or P cells were present in nine of the 18 tumors. Macroscopically, many of the tumors showed IIc or IIc + III type. Histologically, the 18 tumors consisted of six well differentiated adenocarcinomas and 12 poorly differentiated adenocarcinomas including signet-ring cell carcinoma. These 12 tumors frequently developed in the stomach of young females. In view of our previous investigations, it was suggested that the IIc-type argyrophil cell carcinoma histologically showing poorly differentiated adenocarcinoma may be related to scirrhous carcinoma of the stomach.

Scirrhous argyrophil cell carcinoma of the stomach with multiple production of polypeptide hormones, amine, CEA, lysozyme, and HCG

Sixteen argyrophil cell carcinomas in 59 gastric scirrhous carcinomas were examined histologically, ultrastructurally, and immunohistochemically for polypeptide hormones, CEA, lysozyme, and HCG. In nine of these 16 tumors, polypeptides such as gastrin, somatostatin, and glucagon were demonstrated. Six of these nine tumors contained all three hormones, and three of these six tumors also had argentaffin cells. In all of these 16 tumors CEA were observed. Eight of them had CEA, lysozyme, and acid mucin synchronously. Of the above six tumors containing three peptides, three produced focal HCG. Ultrastructurally, several types of secretory granules were noted. Histologically, these 16 tumors showed poorly differentiated adenocarcinomas or signet ring cell carcinomas. Macroscopically, generalized type was 11 and localized type five. No hormonal syndrome was detected in any of the patients. It was suggested that these scirrhous argyrophil cell carcinomas of the stomach with the multifunction originate from totipotent immature cells of endodermal origin.

Gastric carcinomas with argyrophil and argentaffin cells

In series of 248 gastric carcinomas from surgical resections the occurence of argyrophil and argentaffin cells was studied. These cells were distinctly more frequent in diffuse than in tubular carcinomas. In all cases with both types of APUD-cells, argyrophil cells were more numerous than argentaffin cells. These tumors are considered to be a variant of current gastric carcinoma, with more pronounced APUD-differentiation of neoplastic cells. This variant stands apart from carcinoid tumors and also from those rare nasal adenocarcinomas with argentaffin cells.

Villous adenoma of the duodenum: cellular composition and histochemical findings

A villous adenoma of the duodenum was studied histologically and histochemically by semi-thin sections using glycol-methacrylate as embedding medium. All the four epithelial cell types which are present in normal duodenal mucosa (absorptive columnar, goblet, Paneth, endocrine) were found in the tumour, as well as undifferentiated elements. Neutral and acid non-sulphated mucins were detected. Cell type distribution and mucin production varied according to the degree of differentiation. Foci of gastric metaplasia were observed. A possible histogenesis from crypt base stem cell is considered.

The diffuse endocrine system and derived tumours. Histological and histochemical characteristics

The Diffuse Endocrine System, to which the so-called APUD (Amine Precursor Uptake and Decarboxylation) cells do belong, gives rise to a group of tumours which may or not secrete amines and/or polypeptide hormones: carcinoids (argentaffinomas, argentaffin or Kultschitzky cell carcinomas). Foregut carcinoids are predominantly of B type (trabecular), argyrophilic, or non-reactive (in about 70% of cases) to silver impregnation. Midgut tumours are generally of A type (insular); more than 80% of them are argentaffinic. Hindgut derived carcinoids are primarily of mixed type; nearly 70% are non-reactive to silver stains. From a cytological standpoint all types may be build up of either small-round, spindle-shaped, polyhedral or cuboidal cells. From a functional point-of-view, the cells are either clear and immature, non-reducing or exhausted. Accordingly, the diagnosis cannot be based alone on silver impregnation or other histochemical methods.

Distribution of lysozyme, alpha 1-Antichymotrypsin and alpha 1-Antitrypsin in adenocarcinomas of the stomach and large intestine. An immunohistochemical study

Lysozyme, alpha 1-Antichymotrypsin and alpha 1-Antitrypsin were demonstrated by an immunoperoxidase technique (PAP) in malignant cells of adenocarcinomas of the stomach but not of the large intestine. Lymph-node metastases showed identical immunoreactivity to that of the primary tumour. Neoplasms arising from the cardia, the body and the pyloric antrum of the stomach showed different immunostaining reactions. It seems that these differences partly reflect the distribution of lysozyme, alpha 1-Antichymotrypsin and alpha 1-Antitrypsin in the normal gastric mucosa. The usefulness of our findings in the identification of the primary tumour in cases of lymph node metastases of unknown origin, is also discussed.

Endocrine-paracrine cells in pancreatic exocrine carcinomas

Eleven cases of primary pancreatic adenocarcinomas have been investigated histochemically, immunohistochemically and with electron-microscopy. Endocrine-paracrine (EP) cells were present in six of these tumours. In one case numerous 5HT-enterochromaffin cells (EC) of the intestinal type and a few somatostatin immunoreactive D cells were found. Two cases contained insulin-immunoreactive cells and another case displayed glucagon-IR elements. In the remaining two cases argyrophilic cells were present. These findings demonstrate that polypeptide hormone or amine production is not restricted to islet cell tumours. It is suggested that both endocrine and exocrine components of the tumours studied might have derived from a common precursor.

The endocrine component of prostatic carcinomas, mixed adenocarcinoma-carcinoid tumours and non-tumour prostate. Histochemical and ultrastructural identification of the endocrine cells

Two types of endocrine-paracrine (EP) cells have been detected histochemically and ultrastructurally in normal and hyperplastic prostates; i.e. type I cells resembling intestinal EC (enterochromaffin) cells and type 2 cells similar to urethral EP cells previously reported by Casanova et al. (1974). About one-third of the 40 prostatic carcinomas studied contained EP cells: two of these were composite tumours exhibiting both adenocarcinomatous and carcinoid patterns. These four tumours have also been studied histochemically and ultrastructurally. ACTH and beta-endorphin immunoreactive cells, ultrastructurally resembling pituitary corticotrophic cells, have been identified in three tumours. Cells identical with type I and type 2 cells of the normal prostate were detected in two cases and in a further case, respectively.

Atypical gastric carcinoids

Four examples of infiltrating gastric tumours which had light microscopic features suggestive of carcinoid or oat-cell carcinoma are documented. Histological and ultrastructural findings indicated that these tumours were atypical carcinoids. A spectrum of endocrine cell neoplasia in the stomach analogous to that observed in the bronchus is postulated. It is felt that increased recognition of poorly differentiated endocrine tumours of the stomach might be of prognostic and therapeutic importance.

Goblet cell carcinoid of appendix: ultrastructural features and histogenetic aspects

Light and electron microscopic examination of a goblet cell carcinoid revealed cells with pleomorphic neurosecretory-type granules, cells containing mucin some of which also contained these granules and less differentiated cells lacking the aforementioned features. Recent embryologic and anatomic studies of developing avian and mammalian gut, respectively, show that intestinal APUD cells are probably of endodermal origin. Therefore, mixed carcinoid tumors such as the goblet cell variant could arise in crypt base stem cells.

Mucin-producing carcinoid ("composite tumor") of upper third of esophagus: a variant of carcinoid tumor

An unusual upper esophageal polypoid tumor was found to be predominantly a carcinoid tumor and in part a mucin-producing adenocarcinoma. A review of literature showed this to be a unique tumor in this location.

Mucins and carcinoid tumours

Mucin was demonstrated in 11 of 16 carcinoid tumours of usual histological appearances. The mucin was characterized histochemically and shown to be similar to that which is produced in the gastrointestinal as well as the respiratory tract. This relative ubiquity of mucin in carinoid tumours has not hitherto been appreciated and more obviously "mixed" tumours have been regarded as rareties. The importance of these findings with respect to the neural crest theory of origin of enterochromaffin cells is discussed.