Carcinomas and carcinoid tumours of the appendix in a district general hospital.

In a retrospective series of 40 appendiceal tumours occurring over a 10-year period, 30 were carcinoid tumours of classical histological pattern, five were adenocarcinomas, and two were tumours intermediate in pattern between carcinoid and carcinoma. The remaining three tumours were secondaries from primary colonic tumours. The implications of the findings are discussed.     

Nuclear pleomorphism in typical carcinoid tumours of the lung: problems in frozen section interpretation

Pulmonary typical carcinoid tumours are generally easy to diagnose with their uniform cells, carcinoid growth pattern and lack of mitoses. However, nuclear pleomorphism, which is common in other neuroendocrine tumours, is not emphasized in pulmonary carcinoid tumours. Three cases of typical carcinoid tumours, because of marked nuclear pleomorphism on frozen section, were misdiagnosed as non-small cell carcinomas.     

Comparison of immunological detection of 5-hydroxytryptamine by monoclonal antibodies with standard silver stains as an aid to diagnosing carcinoid tumours.

Immunoreactivity to a monoclonal antibody against 5-hydroxytryptamine (5HT) was compared with Churukian Schenk argyrophilia and Masson Fontana argentaffin staining as an aid to the diagnosis of 53 carcinoid tumours. Thirty four tumours were argentaffin positive, 50 were argyrophil positive, and 43 contained immunologically detectable 5HT. In general, argentaffin staining and immunological detection of 5HT failed to pick up tumours derived from the foregut of type B or type D morphology. Argentaffin negative tumours usually showed only focal immunoreactivity for 5HT. If immunological detection of 5HT is used alone as a marker for carcinoid tumours problems arise in the differentiation of carcinoid tumours from adenocarcinomas which may also contain 5HT. These results were compared with those culled from other reported techniques used as an aid to the diagnosis of carcinoid tumours.     

Expression of occludin in human rectal carcinoid tumours as a possible marker for glandular differentiation

AIMS: To examine whether or not the tight junction-associated transmembrane protein occludin is expressed in rosette or gland-like structures in human rectal carcinoid tumours. The tight junction is crucial for the formation and maintenance of organized tubular structures in glandular epithelia. Previous studies have reported the presence of glandular structures in carcinoid tumours, though they are not believed to arise from glandular epithelium. METHODS AND RESULTS: The expression profiles of occludin in 40 carcinoid tumours were examined immunohistochemically, using an anti-occludin monoclonal antibody. In eight (20%) samples of typical carcinoid tumours, a small number of rosette-like tubular structures outlined by occludin were detected. CONCLUSIONS: Tight junction-associated molecules, including occludin, are thought to be one of the most characteristic structural markers of polarized glandular structures. The results of the present study provide supportive evidence that carcinoid tumour cells are capable of glandular differentiation.     

Argentaffin and argyrophil reactions and serotonin content of endocrine tumours.

Sixty carcinoid tumours were tested in a retrospective study with an immunoperoxidase technique using a monoclonal antibody against serotonin immunoreactive sites, with argyrophil staining using the Grimelius technique, and with argentaffin staining using the Masson-Fontana technique. A good correlation between all three techniques in the diagnosis of ileal carcinoid tumour was found, but the immunoperoxidase technique showed greater sensitivity than the Masson-Fontana technique and greater specificity than the Grimelius technique in the diagnosis of foregut and hindgut carcinoid tumours. The immunoperoxidase technique with a monoclonal antibody against serotonin immunoreactive sites (YC5/45) is recommended as a sensitive and specific test for carcinoid tumours. The reactions in other endocrine tumours are also included.     

Prealbumin in the diagnosis of bronchopulmonary carcinoid tumours.

The reliability of prealbumin as a diagnostic marker was studied in 60 cases of bronchopulmonary carcinoid tumours. There were differences in the incidence of positivity between typical and atypical carcinoids (well differentiated neuroendocrine carcinomas). Seventy five per cent of the carcinoid tumours were positive for prealbumin; (86.7% typical and 63.3% atypical carcinoids). In 15 cases, which were Grimelius negative, 10 were prealbumin positive. Only 8.3% carcinoids were negative with both prealbumin and Grimelius stains. Ten squamous, 10 adeno- and 10 small cell carcinomas showed only occasional scattered prealbumin positive cells. It is concluded that prealbumin is a useful marker for bronchopulmonary carcinoid tumours. It is cheap, readily available, and should be considered part of routine diagnostic procedures for the diagnosis of carcinoid tumours.     

Immunohistochemical markers of small cell carcinoma and related neuroendocrine tumours of the lung

A selected group of 263 pulmonary neuroendocrine tumours comprised 156 small cell carcinomas, five combined cell carcinomas, nine atypical carcinoid/small cell carcinomas, 32 atypical carcinoids, ten large cell/small cell carcinomas, and 51 carcinoid tumours. These were compared with a group of 109 non-small cell carcinomas, using four markers of neuroendocrine differentiation to determine differences in reactivity between the two groups and among the variants of neuroendocrine tumour. The antibodies used were neuron-specific enolase (NSE), protein gene product (PGP) 9.5, human bombesin, and the C-terminal flanking peptide of human bombesin (CTP). Most small cell carcinomas, carcinoid tumours, and atypical carcinoid variants showed immunoreactivity for both NSE and PGP 9.5 but a significant number of non-small cell carcinomas, mainly squamous cell carcinomas, were also positive (11 and 35 per cent, respectively). Bombesin was specific for neuroendocrine tumours, being demonstrable in 35 per cent carcinoids and 24 per cent small cell carcinomas, but staining was focal and often confined to scattered cells. Diffuse strongly positive immunoreactivity for CTP was seen in the majority of malignant neuroendocrine tumours, but only 12 per cent of carcinoid tumours were positive and non-small cell carcinomas were negative. CTP is therefore of potential value as a specific marker of malignant neuroendocrine tumours, particularly if the amount of biopsy material is limited and the tumour is an unusual variant, such as atypical carcinoid or large cell-small cell carcinoma.     

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.     

Lack of C-erbB-2 protein expression in pulmonary carcinoid tumours.

To determine if amplification of the C-erb-B2 proto-oncogene could be correlated with prognosis in carcinoid tumours, 49 pulmonary carcinoid tumours (26 typical, 23 atypical) were examined using a polyclonal antibody to the C-terminal peptide of the C-erb-B2 protein sequence. No C-erb-B2 gene product could be shown: the demonstration of C-erb-B2 does not seem to help, therefore, in determining diagnosis or prognosis in pulmonary carcinoid tumours.     

Lectin expression in carcinoid tumours of the gastrointestinal tract

The binding of peroxidase-conjugated Dolichos biflorus (DBA), Triticum vulgaris (WGA), Canavalia ensiformis (Con A), Arachis hypogaea (PNA), Lotus tetragonolobus, and Bandeiraea simplicifolia I (BSAI) to gastrointestinal carcinoid tumours was studied. The results indicate that carcinoid tumour cells express certain carbohydrates similar to those present in the adjacent surface epithelium. The differences in the lectin-binding properties of carcinoid tumours of different sites of the gastrointestinal tract are closely related to the regional differences in the lectin binding of adjacent surface epithelium. These observations therefore form a useful basis for further studies in the application of lectin histochemistry to elucidate the histogenesis of carcinoid tumours.     

Gastrin releasing peptide and gastrin releasing peptide receptor expression in gastrointestinal carcinoid tumours

AIMS: To establish whether gastrin releasing peptide (GRP) and the GRP receptor (GRPR) are expressed together in gastrointestinal carcinoid tumours. METHODS: Twenty six carcinoid tumours from the stomach, small intestine, appendix, and colorectum were investigated by immunohistochemistry for GRP and GRPR. RESULTS: GRP was detected in nine of 19 tumours and GRPR in 22 of 26. Coexpression of both the ligand and receptor was seen in six of 19 cases. GRPR but not GRP was more strongly expressed in appendix and colonic tumours. CONCLUSIONS: GRP and GRPR are produced by a large number of gastrointestinal carcinoid tumours. An autocrine/paracrine pathway may exist for GRP stimulated cell proliferation in some of these neoplasms, analogous to that seen in small cell anaplastic carcinoma of the lung.     

Electron microscopic characteristics of carcinoid tumors of varying localization and degree of differentiation

Results of an electron-microscopic study of 15 carcinoid tumours of different sites were compared to those of histological and histochemical investigation. Highly differentiated tumours (6 observation had pronounced tissue and organ-specific features, contained a high number of argentaffin and/or argyrophilic endocrine granules in all cells. Moderately differentiated tumours (3 observations) showed a typical structure and abundance of secretory granules in the cytoplasm; when the chromatin of their nuclei became coarse, consisting of large clumps, karyolemma invaginations and bulging appeared, this being a sign of malignization. These nuclei changes progressed in the poorly differentiated tumours, number of secretory granules decreased (they were absent in 50% of cells). Argentaffin carcinoid of the appendix, intestine and cecum contained mainly serotonin granules (diameter 200-350 nm) and small number of polypeptide hormones granules (diameter less than 200 nm). The inverse correlation between the granules was observed in the bronchial carcinoid.     

Immunohistochemical study of chromogranin in 100 cases of pheochromocytoma,carotid body tumour,medullary thyroid carcinoma and carcinoid tumour

Summary Neuroendocrine cells have histologically common features represented by argyrophilic cytoplasm containing neuroendocrine granules. Neuroendocrine granules are composed of various kinds of peptide hormones, amines, carrier proteins and ATP. Although various kinds of peptide hormones have been detected in neuroendocrine tumours, a peptide hormone has not been required as a standard marker for these tumours. Chromogranin is a purified protein which binds catecholamines specifically and is recognized as a carrier protein. We carried out an immunohistochemical study of chromogranin immunoreactivity in 100 neuroendocrine tumours including pheochromocytomas, carotid body tumours, medullary thyroid carcinomas and carcinoid tumours. Marked immunoreactivity was observed in 85% of carcinoid tumours and 100% of the other tumour types. A non-functioning paraganglioma and a malignant carcinoid tumour without any other detectable marker also showed strong immunoreactivity to chromogranin. Chromogranin immunoreactivity is a useful tool for neuroendocrine tumours.     

The topographical and age distributions of neuroendocrine cells in the normal human appendix

In order to clarify the histogenesis of appendiceal carcinoid tumours, epithelial (ENC) and subepithelial (SNC) neuroendocrine cells were counted at four sites in 50 normal appendices stained by standard argyrophil and argentaffin techniques. In general, ENC were present in similar number at all sites within the appendix, whereas SNC were more numerous at the tip than at the base. The number of ENC was similar throughout life, apart from an increase in one neonate and some elderly patients, whereas SNC were maximal in young adults. Thus, the topographical and age distributions of SNC, but not those of ENC, parallels the topographical and age incidence of appendiceal carcinoid tumours, suggesting that most appendiceal carcinoid tumours arise from SNC rather than ENC.     

The histogenesis of carcinoid tumours of the rectum

`Carcinoid'' tumours of the rectum have been described which are classified on histological appearances into three main varieties: `true'' carcinoid or argentaffinoma, `atypical'' or non-argentaffin carcinoid, and `composite carcinoid. The histogenesis of these tumours is discussed and it is suggested that non-argentaffin carcinoids of the rectum have an essentially similar histogenesis to certain tumours of the lung, pancreas, and gastrointestinal tract. The difference in growth, pattern, and staining reactions are a reflection of differing directions and levels of differentiation of the parent epithelium. The functional implications of this hypothesis are discussed.     

Serotonin in fore-gut carcinoids. A survey of 60 cases with regard to silver stains, formalin-induced fluorescence and serotonin immunocytochemistry

A series of 60 fore-gut carcinoid tumours was examined with regard to serotonin content after application of three different techniques, namely: the argentaffin reaction, formalin-induced fluorescence according to Falck-Hillarp and immunocytochemistry with monoclonal antibodies to serotonin. To evaluate the staining-fluorescence of individual tumour cells, the methods were applied to identical tumour sections. Twelve tumours demonstrated serotonin-immunoreactive cells, six of which were also argentaffin. Four tumours contained argentaffin cells but no serotonin-immunoreactivity. With the use of all three techniques, three types of tumour cells occurred, namely: serotonin-immunoreactive, non-argentaffin and non-fluorescence cells, serotonin-immunoreactive, argentaffin and fluorescent cells, and non-serotonin immunoreactive, argentaffin and non-fluorescent cells. The first (serotonin-immunoreactive) cell type was most frequently found in the tumours. One gastric carcinoid in which the argentaffin cells exceeded the serotonin-immunoreactive cells, a positive reaction was found with the modified Warthin-Starry reaction for demonstrating melanin. Since none of the techniques used for visualization of serotonin in endocrine tumours is unquestionably specific and since they do not give identical results, it is indicated that for a more accurate identification of serotonin in fore-gut carcinoid tumours, a positive reaction with at least two of the applied techniques is desirable.     

Pigmented spindle cell carcinoid tumour of the thymus with ectopic adrenocorticotropic hormone secretion: report of a rare variant and differential diagnosis of mediastinal spindle cell neoplasms

AIMS: A variety of histological variants of thymic carcinoid tumour have been described. A rare case of pigmented spindle cell carcinoid tumour of the thymus is documented and compared with the reported cases of thymic pigmented carcinoid tumour in the literature, with a discussion of the differential diagnosis of spindle cell tumours of the mediastinum. METHODS AND RESULTS: A thymic tumour with ectopic adrenocorticotropic hormone (ACTH) secretion was resected from a 24-year-old man suffering from Cushing's syndrome. Histological, immunohistochemical, and ultrastructural studies revealed an ACTH-producing spindle cell carcinoid tumour harbouring pigmented melanocytes. Among four thymic pigmented carcinoid tumours reported before, only one was similar to the present case by being also an ACTH-secreting pigmented spindle cell thymic carcinoid tumour. The clinicopathological features of this tumour distinguish it from a spindle cell thymoma, spindle cell thymic carcinoma, and other mediastinal spindle cell tumours. CONCLUSIONS: This case illustrates an extremely rare variant of thymic carcinoid tumour exhibiting a spindle cell morphology and harbouring pigmented melanocytes. Awareness of this histological variant is important in the differential diagnosis of spindle cell tumours of the mediastinum.     

Sox10-positive sustentacular cells in neuroendocrine carcinoma of the lung

Tsuta K, Raso M G, Kalhor N, Liu D C, Wistuba I I & Moran C A
(2011) Histopathology  58, 276–285
Sox10‐positive sustentacular cells in neuroendocrine carcinoma of the lung Aims: Sustentacular cells are found in approximately half of pulmonary carcinoid tumours. However, most studies of sustentacular cells have used the less‐specific antibody to the S100 protein, and any correlation between the presence of sustentacular cells and other clinicopathological factors is unclear. The aim of this study was to analyse the significance of sustentacular cells in pulmonary neuroendocrine carcinomas (NECs). Methods and results: A Sox10 antibody was used to investigate 113 pulmonary NECs. Sustentacular cells were observed in 66.7% of typical carcinoid (TC) and 58.3% of atypical carcinoid (AC) cases, but not in high‐grade NECs. Sustentacular‐rich tumours had a statistically significant correlation with peripheral locations. We found no statistical differences in age, gender, smoking history, overall survival, or the occurrence of lymph node metastasis. In all but one case, when sustentacular cells were present in the primary site, they were also present in the metastatic lymph nodes. The presence of sustentacular cells differed in morphological subtypes, with the spindle pattern being the most common subtype. Conclusions: Sox10‐positive sustentacular cells were observed in carcinoid tumours but not in high‐grade NECs. Sustentacular‐rich carcinoid tumours did not show a correlation with the occurrence of lymph node metastasis or survival. The sustentacular cells found differed in morphological subtypes.     

Duodenal and ampullary carcinoid tumors

Summary Twelve duodenal carcinoid tumours are presented, 4 of them located in the ampulla. Symptoms included the Zollinger-Ellison syndrome (4 patients), the carcinoid syndrome (1 patient), mechanical obstruction (3 patients), bleeding (1 patient) and abdominal pain (1 patient). Two further tumours were detected by chance.Three patients with the Zollinger-Ellison syndrome had additional endocrine tumours characteristic of the MEN I syndrome. In 2 of them the duodenal carcinoids were of very small size and were multiple. They were observed in close proximity to focal areas of endocrine cell hyperplasia.Immunohistochemical investigations showed gastrin and somatostatin to be the predominant polypeptide hormones produced by these tumours. No somatostatinoma syndrome was encountered. In half of our cases additional production of insulin, VIP or even calcitonin in smaller amounts was found.Two of our patients had cutaneous manifestations of von Recklinghausen's disease and in both of them the carcinoid was located in the ampulla. One of these patients also had a pheochromocytoma.