Carcinoid tumors of the pancreas. Status report based on two cases and review of the world's literature

Epidemiology and Prognostic Nomogram for Predicting Long-Term Disease-Specific Survival in Patients With Pancreatic Carcinoid Tumor: A SEER-Based Study

OBJECTIVES

Pancreatic carcinoid tumor (PCT) is described as a malignant form of carcinoid tumors. However, the epidemiology and prognostic factors for PCT are poorly understood.

MATERIALS AND METHODS

The data of 2447 PCT patients were included in this study from the Surveillance, Epidemiology, and End Results database and randomly divided into a training cohort (1959) and a validation cohort (488). The epidemiology of PCT was calculated, and independent prognostic factors were identified to construct a prognostic nomogram for predicting long-term disease-specific survival (DSS) among PCT patients.

RESULTS

The incidence of PCT increased remarkably from 2000 to 2018. The 1-, 5-, and 10-year DSS rates were 96.4%, 90.3%, and 86.5%, respectively. Age at diagnosis, stage, surgery, radiotherapy, and chemotherapy were identified as independent prognostic factors to construct a prognostic nomogram. The C -indices; area under the receiver operating characteristic curves for predicting 1-, 5-, and 10-year DSS, and calibration plots of the nomogram in both cohorts indicated a high discriminatory accuracy, preferable survival predictive ability, and optimal concordances, respectively.

CONCLUSIONS

The incidence of PCT has increased rapidly since 2000. In addition, we established a practical, effective, and accurate prognostic nomogram for predicting the long-term DSS of PCT patients.

The risk and prognostic factors for G1 pancreatic neuroendocrine tumors: A retrospective analysis of the SEER database

Background

Pancreatic neuroendocrine tumors (pNETs) are rare neuroendocrine neoplasms (NENs) for which little is known about their clinical features, treatment options, and survival prognosis. The purpose of this study is to evaluate the risk factors affecting the overall survival (OS) and cancer-specific survival (CSS) in patients with grade 1 pNETs (G1 pNETs) and to provide a new theoretical basis for clinical diagnosis and treatment.

Methods

A retrospective analysis of individuals with G1 pNETs registered in the Surveillance, Epidemiology, End Results (SEER) database was performed. Risk factors affecting OS and CSS were analyzed using Kaplan-Meier analysis, Cox proportional hazards model, and Fine-Gray competing-risk model.

Results

A total of 751 patients were included, most of whom were white (77.2%) women (53.9%) under the age of 60 years (54.9%), of whom 66 died of pNETs (8.78%) and 34 died of other causes (4.52%). Patients who were older than 60 years at diagnosis (hazard ratio [HR] = 1.866, 95% confidence interval [CI]: 1.242-2.805) had worse OS. And stage in the regional extent (HR = 1.777, 95% CI: 1.006-3.137) or distance extent (HR = 4.540, 95% CI: 2.439-8.453) had worse OS. Patients who delayed treatment after diagnosis had shorter CSS (delayed treatment < 1 month: HR = 1.933, 95% CI: 0.863-4.333; delayed treatment ≥ 1 month: HR = 2.208; 95% CI:1.047-4.654). Patients with lymph node metastasis (HR = 1.989, 95% CI: 1.137-3.479) or distant metastasis (HR = 5.625, 95% CI: 1.892-16.726) had worse CSS. Acceptance of surgery can significantly improve the patient’s OS and CSS. OS (partial pancreatectomy [PP]: HR = 0.350, 95% CI: 0.182-0.672; pancreatectomy and duodenectomy [PD]: HR = 0.426, 95% CI: 0.222-0.815; total pancreatectomy [TP]: HR = 0.495, 95% CI: 0.193-1.267). CSS(PP: HR = 0.148, 95% CI: 0.0054-0.401; PD: HR = 0.332, 95% CI: 0.150-0.730; TP: HR = 0.69, 95% CI: 0.254-1.872).

Conclusion

Age and stage were identified as independent risk factors for OS. Delayed treatment, N stage and M stage were independent risk factors for CSS. Only surgery was identified as independent protective factors for OS and CSS.

Serotonin-Secreting Neuroendocrine Tumours of the Pancreas

Background: Serotonin-secreting pancreatic neuroendocrine tumours (5-HT-secreting pNETs) are very rare, and characterised by high urinary 5-hydroxyindole-acetic acid (5-HIAA) levels (or high serum 5-HT levels). Methods: Patients with 5-HT-secreting pancreatic neoplasms observed in our unit (1986–2015) were included. Diagnosis was based on urinary 5-HIAA or serum 5-HT levels. Results: Seven patients were enrolled (4 M/3 F), with a median age of 64 (range 38–69) years. Two patients had a carcinoid syndrome. Serum 5-HT was elevated in four patients. Urinary 5-HIAA levels were positive in six patients. The median tumour size was 4.0 (range 2.5–10) cm. All patients showed liver metastases at diagnosis. None underwent resective surgery; lymph node/liver biopsies were taken. Six lesions were well-differentiated tumours and one a poorly differentiated carcinoma (Ki67 range 3.4–70%). All but one patient received chemotherapy. Four patients received somatostatin analogues; three patients underwent ablation of liver metastases. One patient is alive with disease 117 months after observation. All the others died from disease progression after a follow-up within 158 months. Conclusions: Primary 5-HT-secreting pNETs are mostly metastatic to the liver; patients are not amenable to resective surgery. Despite high 5-HIAA urinary levels, few patients present with carcinoid syndrome. A five-year survival rate of 42.9% may be achieved with multimodal treatment.

Neoplasms of the Neuroendocrine Pancreas: An Update in the Classification, Definition, and Molecular Genetic Advances

This review focuses on discussing the main modifications of the recently published 2017 WHO Classification of Neoplasms of the Neuroendocrine Pancreas (panNEN). Recent updates separate pancreatic neuroendocrine tumors into 2 broad categories: well-differentiated pancreatic neuroendocrine tumors (panNET) and poorly differentiated pancreatic neuroendocrine carcinoma (panNEC), and incorporates a new subcategory of "well-differentiated high-grade NET (G3)" to the well-differentiated NET category. This new classification algorithm aims to improve the prediction of clinical outcomes and survival and help clinicians select better therapeutic strategies for patient care and management. In addition, these neuroendocrine neoplasms are capable of producing large quantity of hormones leading to clinical hormone hypersecretion syndromes. These functioning tumors include, insulinomas, glucagonomas, somatostatinomas, gastrinomas, VIPomas, serotonin-producing tumors, and ACTH-producing tumors. Although most panNENs arise as sporadic diseases, a subset of these heterogeneous tumors present as parts on inherited genetic syndromes, such as multiple endocrine neoplasia type 1, von Hippel-Lindau, neurofibromatosis type 1, tuberous sclerosis, and glucagon cell hyperplasia and neoplasia syndromes. Characteristic clinical and morphologic findings for certain functioning and syndromic panNENs should alert both pathologists and clinicians as appropriate patient management and possible genetic counseling may be necessary.

Endoscopic ultrasound appearance of pancreatic serotonin-staining neuroendocrine neoplasms

BACKGROUND/OBJECTIVES

The pancreatic localization of serotonin-staining neuroendocrine neoplasms is extremely rare. This is a retrospective study aimed at analyzing the endoscopic ultrasound appearance of pancreatic serotoninoma.

METHODS

Between 2010 and 2016, all consecutive patients with histologically proven pancreatic serotoninoma who had undergone endoscopic ultrasound were enrolled.

RESULTS

Eight patients (six F, median age 68.5 years) had a diagnosis of pancreatic serotoninoma and underwent endoscopic ultrasound examinations. Median diameter of the lesion was ten mm. The nodule echotexture was hypoechoic in seven out of eight cases. The most frequent localization was the pancreatic neck (four); in three cases, the tumor was located in the pancreatic head and in one in the body. In seven cases the tumor caused a main pancreatic duct dilation; in three cases also the secondary ducts were dilated. In one case a dilation of the common bile duct was observed. At contrast-enhanced endoscopic ultrasound no one showed the typical contrast-enhancement. Elastography (available in two patients) showed a rigid pattern of the lesion.

CONCLUSIONS

From this case series a specific endoscopic ultrasound appearance resulted for pancreatic serotoninoma, different from other types of pancreatic neuroendocrine neoplasm, but it is difficult to differentiate it from a pancreatic adenocarcinoma or an intraductal papillary mucinous neoplasm.

Pancreatic carcinoids (serotonin-producing pancreatic neuroendocrine neoplasms): Report of 5 cases and review of the literature

INTRODUCTION

Pancreatic neuroendocrine neoplasms (pNENs) are relatively rare tumors representing 1% to 2% of all pancreatic neoplasms. These tumors can secrete a variety of biologically active substances giving rise to distinct clinical symptoms or can be clinically nonfunctioning. Apart from insulinomas and gastrinomas, which constitute the majority of functioning pNENs, some tumors may secrete serotonin presenting with the features of the carcinoid syndrome. These so-called pancreatic carcinoids are considered relatively rare tumors and are associated with increased urinary levels of 5-hydroxyindoleacetic acid (5-HIAA). It has recently been suggested that the prevalence of such tumors might be underestimated.

CASES

We present a series of 5 patients from our database of 138 pNENs (5/138, 3.62%), harboring serotonin-producing pNENs and describe their distinctive clinical, biochemical, histopathological features, and response to treatment along with a review of the relevant available literature.

CONCLUSION

Such tumors are considered rare, although this may be an underestimate as systematic screening for the presence of serotonin in tissue or elevated urinary 5-HIAA levels in patients with apparently nonfunctioning pNENs is not currently recommended. In order to reach such a consensus, data from large prospective studies are needed in order to evaluate the impact of this type of tumors in survival and clinical outcome, since some studies have suggested a worse prognosis.

Carcinoid syndrome from a carcinoid tumor of the pancreas without liver metastases: A case report and literature review

A carcinoid tumor of the pancreas (CTP) is a rare pancreatic neoplasm, and usually presents with carcinoid syndrome (CS). CS consists of the classic symptom triad of cutaneous flushing, diarrhea and valvular disease, and occurs in the majority of patients with liver metastases. In the present study, the patient presented with symptoms of CS. A diagnosis of CTP with CS was suspected due to high levels of urine 5-hydroxyindolacetic acid, and this was confirmed by a fine-needle aspiration biopsy. Computed tomography showed extended lymphadenopathy, but no liver metastases. The patient was managed conservatively with octreotide long acting repeatable. To the best of our knowledge, this is the second literature case of CS associated with CTP without liver metastases.

Uncommon presentations of common pancreatic neoplasms: a pictorial essay

Pancreatic neoplasms are a wide group of solid and cystic lesions with different and often characteristic imaging features, clinical presentations, and management. Among solid tumors, ductal adenocarcinoma is the most common: it arises from exocrine pancreas, comprises about 90% of all pancreatic neoplasms, and generally has a bad prognosis; its therapeutic management must be multidisciplinary, involving surgeons, oncologists, gastroenterologists, radiologists, and radiotherapists. The second most common solid pancreatic neoplasms are neuroendocrine tumors: they can be divided into functioning or non-functioning and present different degrees of malignancy. Cystic pancreatic neoplasms comprise serous neoplasms, which are almost always benign, mucinous cystic neoplasms and intraductal papillary mucinous neoplasms, which can vary from benign to frankly malignant lesions, and solid pseudopapillary tumors. Other pancreatic neoplasms, such as lymphoma, metastases, or pancreatoblastoma, are rarely seen in clinical practice and have different and sometimes controversial managements. Rare clinical presentations and imaging appearance of the most common pancreatic neoplasms, both solid and cystic, are more frequently seen and clinically relevant than rare pancreatic tumors; their pathologic and radiologic appearances must be known to improve their management. The purpose of this paper is to present some rare or uncommon clinical and radiological presentations of common pancreatic neoplasms providing examples of multi-modality imaging approach with pathologic correlations, thus describing the histopathological bases that can explain the peculiar imaging features, in order to avoid relevant misdiagnosis and to improve lesion management.

Clinical Presentation and Diagnosis of Pancreatic Neuroendocrine Tumors

Pancreatic neuroendocrine tumors are a rare group of neoplasms that arise from multipotent stem cells in the pancreatic ductal epithelium. Although they comprise only 1% to 2% of pancreatic neoplasms, their incidence is increasing. Most pancreatic neuroendocrine tumors are nonfunctioning, but they can secrete various hormones resulting in unique clinical syndromes. Clinicians must be aware of the diverse manifestations of this disease, as the key step to management of these rare tumors is to first suspect the diagnosis.

BJ-1108, a 6-Amino-2,4,5-Trimethylpyridin-3-ol Analog, Inhibits Serotonin-Induced Angiogenesis and Tumor Growth through PI3K/NOX Pathway

5-Hydroxytryptamine (5-HT) induces proliferation of cancer cells and vascular cells. In addition to 5-HT production by several cancer cells including gastrointestinal and breast cancer, a significant level of 5-HT is released from activated platelets in the thrombotic environment of tumors, suggesting that inhibition of 5-HT signaling may constitute a new target for antiangiogenic anticancer drug discovery. In the current study we clearly demonstrate that 5-HT-induced angiogenesis was mediated through the 5-HT₁ receptor-linked Gβγ/Src/PI3K pathway, but not through the MAPK/ERK/p38 pathway. In addition, 5-HT induced production of NADPH oxidase (NOX)-derived reactive oxygen species (ROS). In an effort to develop new molecularly targeted anticancer agents against 5-HT action in tumor growth, we demonstrate that BJ-1108, a derivative of 6-amino-2,4,5-trimethylpyridin-3-ol, significantly inhibited 5-HT-induced angiogenesis. In addition, BJ-1108 induced a significant reduction in the size and weight of excised tumors in breast cancer cell-inoculated CAM assay, showing proportionate suppression of tumor growth along with inhibition of angiogenesis. In human umbilical vein endothelial cells (HUVECs), BJ-1108 significantly suppressed 5-HT-induced ROS generation and phosphorylation of PI3K/Akt but not of Src. Unlike NOX inhibitors, BJ-1108, which showed better antioxidant activity than vitamin C, barely suppressed superoxide anion induced by mevalonate or geranylgeranyl pyrophosphate which directly activates NOX without help from other signaling molecules in HUVECs, implying that the anti-angiogenic action of BJ-1108 was not mediated through direct action on NOX activation, or free radical scavenging activity. In conclusion, BJ-1108 inhibited 5-HT-induced angiogenesis through PI3K/NOX signaling but not through Src, ERK, or p38.

Down-regulation of 5-HT1B and 5-HT1D receptors inhibits proliferation, clonogenicity and invasion of human pancreatic cancer cells

Pancreatic ductal adenocarcinoma is characterized by extensive local tumor invasion, metastasis and early systemic dissemination. The vast majority of pancreatic cancer (PaCa) patients already have metastatic complications at the time of diagnosis, and the death rate of this lethal type of cancer has increased over the past decades. Thus, efforts at identifying novel molecularly targeted therapies are priorities. Recent studies have suggested that serotonin (5-HT) contributes to the tumor growth in a variety of cancers including prostate, colon, bladder and liver cancer. However, there is lack of evidence about the impact of 5-HT receptors on promoting pancreatic cancer. Having considered the role of 5-HT-1 receptors, especially 5-HT_1B and 5-HT_1D subtypes in different types of malignancies, the aim of this study was to investigate the role of 5-HT_1B and 5-HT_1D receptors in PaCa growth and progression and analyze their potential as cytotoxic targets. We found that knockdown of 5-HT_1B and 5-HT_1D receptors expression, using specific small interfering RNA (siRNA), induced significant inhibition of proliferation and clonogenicity of PaCa cells. Also, it significantly suppressed PaCa cells invasion and reduced the activity of uPAR/MMP-2 signaling and Integrin/Src/Fak-mediated signaling, as integral tumor cell pathways associated with invasion, migration, adhesion, and proliferation. Moreover, targeting 5-HT_1B and 5-HT_1D receptors down-regulates zinc finger ZEB1 and Snail proteins, the hallmarks transcription factors regulating epithelial-mesenchymal transition (EMT), concomitantly with up-regulating of claudin-1 and E-Cadherin. In conclusion, our data suggests that 5-HT_1B– and 5-HT_1D–mediated signaling play an important role in the regulation of the proliferative and invasive phenotype of PaCa. It also highlights the therapeutic potential of targeting of 5-HT_1B/1D receptors in the treatment of PaCa, and opens a new avenue for biomarkers identification, and valuable new therapeutic targets for managing pancreatic cancer.

Causes of death and prognostic factors in multiple endocrine neoplasia type 1: a prospective study: comparison of 106 MEN1/Zollinger-Ellison syndrome patients with 1613 literature MEN1 patients with or without pancreatic endocrine tumors

Multiple endocrine neoplasia type 1 (MEN1) is classically characterized by the development of functional or nonfunctional hyperplasia or tumors in endocrine tissues (parathyroid, pancreas, pituitary, adrenal). Because effective treatments have been developed for the hormone excess state, which was a major cause of death in these patients in the past, coupled with the recognition that nonendocrine tumors increasingly develop late in the disease course, the natural history of the disease has changed. An understanding of the current causes of death is important to tailor treatment for these patients and to help identify prognostic factors; however, it is generally lacking.To add to our understanding, we conducted a detailed analysis of the causes of death and prognostic factors from a prospective long-term National Institutes of Health (NIH) study of 106 MEN1 patients with pancreatic endocrine tumors with Zollinger-Ellison syndrome (MEN1/ZES patients) and compared our results to those from the pooled literature data of 227 patients with MEN1 with pancreatic endocrine tumors (MEN1/PET patients) reported in case reports or small series, and to 1386 patients reported in large MEN1 literature series. In the NIH series over a mean follow-up of 24.5 years, 24 (23%) patients died (14 MEN1-related and 10 non-MEN1-related deaths). Comparing the causes of death with the results from the 227 patients in the pooled literature series, we found that no patients died of acute complications due to acid hypersecretion, and 8%-14% died of other hormone excess causes, which is similar to the results in 10 large MEN1 literature series published since 1995. In the 2 series (the NIH and pooled literature series), two-thirds of patients died from an MEN1-related cause and one-third from a non-MEN1-related cause, which agrees with the mean values reported in 10 large MEN1 series in the literature, although in the literature the causes of death varied widely. In the NIH and pooled literature series, the main causes of MEN1-related deaths were due to the malignant nature of the PETs, followed by the malignant nature of thymic carcinoid tumors. These results differ from the results of a number of the literature series, especially those reported before the 1990s. The causes of non-MEN1-related death for the 2 series, in decreasing frequency, were cardiovascular disease, other nonendocrine tumors > lung diseases, cerebrovascular diseases. The most frequent non-MEN1-related tumor deaths were colorectal, renal > lung > breast, oropharyngeal. Although both overall and disease-related survival are better than in the past (30-yr survival of NIH series: 82% overall, 88% disease-related), the mean age at death was 55 years, which is younger than expected for the general population.Detailed analysis of causes of death correlated with clinical, laboratory, and tumor characteristics of patients in the 2 series allowed identification of a number of prognostic factors. Poor prognostic factors included higher fasting gastrin levels, presence of other functional hormonal syndromes, need for >3 parathyroidectomies, presence of liver metastases or distant metastases, aggressive PET growth, large PETs, or the development of new lesions.The results of this study have helped define the causes of death of MEN1 patients at present, and have enabled us to identify a number of prognostic factors that should be helpful in tailoring treatment for these patients for both short- and long-term management, as well as in directing research efforts to better define the natural history of the disease and the most important factors determining long-term survival at present.

Pancreatic neuroendocrine tumors: biology, diagnosis,and treatment

Pancreatic neuroendocrine tumors (PNETs), a group of endocrine tumors arising in the pancreas, are among the most common neuroendocrine tumors. The genetic causes of familial and sporadic PNETs are somewhat understood, but their molecular pathogenesis remains unknown. Most PNETs are indolent but have malignant potential. The biological behavior of an individual PNET is unpredictable; higher tumor grade, lymph node and liver metastasis, and larger tumor size generally indicate a less favorable prognosis. Endocrine testing, imaging, and histological evidence are necessary to accurately diagnose PNETs. A 4-pronged aggressive treatment approach consisting of surgery, locoregional therapy, systemic therapy, and complication control has become popular in academic centers around the world. The optimal application of the multiple systemic therapeutic modalities is under development; efficacy, safety, availability, and cost should be considered when treating a specific patient. The clinical presentation, diagnosis, and treatment of specific types of PNETs and familial PNET syndromes, including the novel Mahvash disease, are summarized.

Small serotonin-positive pancreatic endocrine tumors caused obstruction of the main pancreatic duct

We report 2 cases of pancreatic endocrine tumors that caused obstruction of the main pancreatic duct (MPD). A 49-year-old asymptomatic man was referred to our institution because dilation of the MPD was revealed by abdominal ultrasonography (US). No tumor was detected by endoscopic ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI). The diameter of the MPD was > 20 mm at the body, and no dilation was noted at the head. Although malignancy was not confirmed through cytology or imaging, pancreatic cancer was strongly suspected. Pancreaticoduo- denectomy was performed. Pathological and immunohistochemical examination revealed a 5 mm × 3 mm serotonin-positive endocrine tumor. Fibrosis was present around the MPD and seemed to cause stricture. A 32-year-old asymptomatic man had elevated serum amylase, and US demonstrated dilation of the MPD. No tumor was detected by CT and MRI. Pancreatic cancer was suspected due to stricture and dilation of the MPD. Pancreatectomy of middle part of pancreas was performed. Pathological and immunohistochemical examination revealed a serotonin-positive endocrine tumor sized 5 mm × 4 mm. We report 2 cases of serotonin-positive pancreatic endocrine tumors that caused stricture of the MPD in spite of the small size of the tumor.

Serotonin expression in pancreatic neuroendocrine tumors correlates with a trabecular histologic pattern and large duct involvement

Pancreatic neuroendocrine tumors with prominent stromal fibrosis are often clinically, radiographically, and grossly indistinguishable from ductal adenocarcinoma. We recently described a small series of fibrotic pancreatic neuroendocrine tumors that express serotonin. To understand better the relationship between histopathologic patterns and serotonin expression, we reviewed 361 pancreatic neuroendocrine tumors to identify those with prominent stromal fibrosis exceeding 30% of total tumor area. We identified 52 cases and immunolabeled these neoplasms with antibodies to serotonin and Ki-67. Two predominant histologic subtypes were identified: 14 (26.9%) of 52 had a trabecular or trabecular-glandular cellular pattern with interspersed fibrosis, whereas 38 (73.1%) of 52 had solid architecture. Of the 52, 14 (26.9%) pancreatic neuroendocrine tumors showed at least focal serotonin immunoreactivity. Tumors with predominantly trabecular architecture were significantly more likely to express serotonin than those with solid architecture (P < .01). Only 2 of 34 pancreatic neuroendocrine tumors with fibrosis less than 30% of total tumor area expressed serotonin. The 14 serotonin-expressing tumors were less likely to have lymph node metastases (P = .016) and more likely to involve large pancreatic ducts (P < .01) than were the 38 serotonin-negative tumors. The serotonin-expressing tumors were also found in a younger patient population (P < .01). There was no significant association of serotonin immunoreactivity with Ki-67 proliferation index, tumor size, or distant metastases. Our data demonstrate a strong correlation between trabecular architecture and serotonin immunoreactivity in pancreatic neuroendocrine tumors with stromal fibrosis. Serotonin-expressing tumors are also less likely to have lymph node metastases and more likely to involve large pancreatic ducts.

Small serotonin-producing neuroendocrine tumor of the pancreas associated with pancreatic duct obstruction

OBJECTIVE

Pancreatic neuroendocrine tumors expressing serotonin (carcinoid tumors) account for a small portion of pancreatic neuroendocrine tumors. The purpose of this study was to describe cases of small serotonin-producing pancreatic neuroendocrine tumors associated with pancreatic duct obstruction.

CONCLUSION

Serotonin produced by pancreatic neuroendocrine tumors can induce fibrosis and pancreatic duct obstruction. Pancreatic neuroendocrine tumors should be considered when CT shows a small hypervascular mass associated with upstream pancreatic duct dilatation or atrophy. Evidence of small pancreatic neuroendocrine tumors should be sought in cases of idiopathic pancreatic duct stenosis.

Serotonin-producing enterochromaffin cell tumors of the pancreas: clinicopathologic study of 15 cases and comparison with intestinal enterochromaffin cell tumors

OBJECTIVES

Serotonin-producing tumors of the pancreas are rare endocrine neoplasms composed of enterochromaffin (EC) cells that have been mainly described in the literature as case reports. This study analyzes the clinicopathologic features of a series of pancreatic EC cell neoplasms and their similarities to and differences from intestinal EC cell tumors.

METHODS

The morphological, immunohistochemical, ultrastructural, and fluorescent in situ hybridization features of 15 pancreatic and 20 intestinal serotonin-producing neoplasms were compared. In addition, we reviewed the literature on pancreatic serotonin-producing tumors to better understand the clinicopathologic features of this rare tumor type.

RESULTS

The lack of substance P and acidic fibroblast growth factor immunoreactivity; the low immunohistochemical expression of CDX2, vesicular monoamine transporter 1, connective tissue growth factor, and prostatic acid phosphatase; the lack of S100-positive sustentacular cells; the strong expression of vesicular monoamine transporter 2; and peculiar ultrastructural features characterize pancreatic EC cell tumors and differentiate them from intestinal ones, although both categories show similar chromosome 18 cytogenetic alterations. The review of the literature indicates that pancreatic functioning tumors associated with the carcinoid syndrome arise in younger patients and are larger, more frequently malignant, and more aggressive neoplasms than pancreatic nonfunctioning ones.

CONCLUSIONS

Pancreatic EC cell tumors show several different morphological features compared with related intestinal tumors despite similar cytogenetic alterations on chromosome 18.

Primary neuroendocrine tumors of the main pancreatic duct: a rare entity

Very few cases of primary neuroendocrine tumors of the main pancreatic duct have been reported. This paucity has hampered an accurate description of the distinctive clinical and pathological features of these tumors and the correct evaluation of the diagnostic and therapeutic problems which they may raise. We report here five additional cases in order to underline the clinical, histological, and immunohistochemical features of this tumor entity. There were three male and two female, aged 43-72 years; in all patients, but one, who presented with epigastric pain, the diagnosis was made after the incidental discovery of a dilatation of the main pancreatic duct. The preoperative diagnosis was ductal adenocarcinoma in one case, IPMN in one case and neoplastic stenosis of unknown etiology in four cases. Surgical resection was performed in all cases. The diagnosis of neuroendocrine tumor was made at histological examination. All lesions were small, ranging from 5 to 15 mm. They had a predominantly intramural growth. The growth pattern was nodular in three cases, circumferential in two; there was no intra-luminal component. All cases were well-differentiated neuroendocrine neoplasms of low histological grade (G1); four cases expressed serotonin. One case was associated with regional lymph node metastases. All cases were cured by surgery alone; no recurrence was observed at the end of the follow-up period. In conclusion, despite their rarity, primary neuroendocrine tumors of the main pancreatic duct deserve recognition and must be considered in the etiological diagnosis of ductal stenosis.

Endocrine tumours of the pancreas

Verbeke C S (2010) Histopathology 56, 669-682 Endocrine tumours of the pancreas Histopathology reporting of pancreatic endocrine neoplasms is complex. The tumours can exhibit a variety of morphological appearances, which often require careful differential diagnostic consideration. Prediction of tumour behaviour and clinical outcome is based on the World Health Organization classification and TNM staging and grading system, which share some criteria and premises, but differ significantly in others. Clinicopathological correlation through discussion at multidisciplinary team meetings is of paramount importance. In this review special emphasis is given to the items of information that can and should be provided by the pathologist to allow optimal patient management. The review further discusses areas of current controversy and uncertainty, of which pathologists participating in multidisciplinary discussions should be aware.

Pancreatic duct stenosis secondary to small endocrine neoplasms: a manifestation of serotonin production?

PURPOSE

To determine if serotonin production by pancreatic endocrine neoplasms is associated with the pancreatic duct stenosis seen in patients with stenosis that is out of proportion to the size of the tumors seen on computed tomographic images.

MATERIALS AND METHODS

Institutional approval was obtained for this HIPAA-compliant study. Informed consent was waived. Clinical and radiologic findings in six patients were reviewed. Gross and histologic findings in the resected pancreata were also assessed. Formalin-fixed paraffin-embedded tumor sections were immunolabeled with antibodies to serotonin. Tissue microarrays constructed from 47 pancreatic endocrine neoplasms from the institutional tissue bank served as controls. Histologic and serotonin immunoreactivity findings were compared between the two groups. The Fisher exact test was used to compare serotonin immunoreactivity.

RESULTS

Only one of the six study patients had a large dominant tumor (4 cm in the pancreatic head). All others were 2.5 cm or smaller. Four of the six pancreatic endocrine neoplasms with associated pancreatic duct stricture had prominent stromal fibrosis. Serotonin immunoreactivity was present in five (83%) patients, and this labeling was strong and diffuse in the four patients with prominent fibrosis. By contrast, stromal fibrosis was minimal in the nonimmunoreactive case. Only three (6%) of the 47 control pancreatic endocrine neoplasms were immunoreactive for serotonin (P < .01, Fisher exact test).

CONCLUSION

These data suggest that serotonin produced by pancreatic endocrine neoplasms may be associated with local fibrosis and stenosis of the pancreatic duct. Clinicians should be aware that small pancreatic endocrine neoplasms can produce pancreatic duct stenosis resulting in ductal dilatation and/or upstream pancreatic atrophy out of proportion to the size of the tumor.

[Carcinoid of pancreas--case report]

INTRODUCTION

Carcinoid tumors are very common tumors of gastro-intestinal tract even though they are very rare in pancreatic area. A large number of patients with pancreatic carcinoma have nonspecific symptoms of disease which is the main cause of late operative treatment of advanced tumors as well as for a low rate of 5-years surviving (28,9% +/- 16%).

CASE REPORT

A 69-year-old female patient was operated for a 7 cm large carcinoid in pancreatic corpus. Prior to the operation the patient did not have any symptoms of disease. Serotonin and 5-HIAA level was normal before the operation as well as afterwards. In this case distal hemipancreatectomy was done along with celiac, hepatic and lienal lymphadenoctomy. Liver metastasis was not found. The diagnosis of carcinoid was verified by postoperative histopathologic and imunohistochemical analysis.

DISCUSSION

According to the experience of other authors, the operative treatment of pancreatic carcinoid is very often undertaken when dimensions of tumor exceed 7 cm. In this stage of disease distant metastases are present in more than 60% of patients. Only 23% of examinated patients have had carcinoid syndrome symptoms. According to this conclusion, the main role of diagnostic procedures is attributed to the computer tomography of abdomen as well as ERCP. The radical resection of pancreas with lymphadenectomy is recommended in order to have a precise histological examination and detect occult lymph node metastases. With radical surgical procedures even at this stage of disease the operation may be curative.

CONCLUSION

Any kind of radical surgical treatment (depending of localizations of tumor, proximal or distal) is the main therapeutic procedure in pancreatic carcinoid.

Changing incidence of pancreatic neoplasms: a 16-year review of statewide tumor registry

OBJECTIVES

Although most pancreatic neoplasms are adenocarcinoma, there are many other histological types, some of which may be increasing in frequency. To better define these trends, we reviewed 16 years of data from a statewide tumor registry.

METHODS

Using the State of Michigan tumor registry, all patients with primary pancreatic cancers from 1986 to 2002 were identified, and patients were excluded if there were insufficient data or the histological subtype was not clearly defined in the literature.

RESULTS

There were 17,610 pancreatic neoplasms identified, and 2425 were excluded, leaving a final population of 15,185. Twenty-five types of primary pancreatic neoplasms were identified. The most common were adenocarcinoma, mucinous cystadenocarcinoma, nonfunctional neuroendocrine, adenosquamous, anaplastic, intraductal papillary mucinous, and acinar cell (8.37, 0.43, 0.18, 0.05, 0.04, 0.04, and 0.02 per 100,000 per year, respectively). The mean age at presentation was similar for tumor types, 69.2 years old, with the exception of endocrine neoplasms occurring at a younger age, 58.5 years old (P < 0.0005). There was a significant change in the incidence of nonfunctional neuroendocrine neoplasms, greater than 2-fold increase (P = 0.0003).

CONCLUSIONS

The incidence of most pancreatic neoplasms has changed a little; however, nonfunctional neuroendocrine neoplasms increased greater than 2-fold. The etiology of this change is unclear.

Endocrine pancreatic tumors: diagnosis and treatment

Endocrine pancreatic tumors (EPTs) are uncommon, having an incidence of one per 100,000 people. They may appear as sporadic tumors or be associated with hereditary syndromes. EPTs are categorized as functioning or nonfunctioning tumors, based on the presence or absence of clinical syndromes. Among the former, insulinomas and gastrinomas are the most common. For the histopathological investigation of EPTs, chromogranin A and synaptophysin immunostainings are recommended. Measurement of circulating chromogranin A is also the cornerstone for the biochemical diagnosis of these tumors. Furthermore, specific hormones produced and released by the neoplastic cells can be identified by immunostaining and used for biochemical evaluation. To locate EPTs, both noninvasive (ultrasonography, computerized tomography, MRI and radionuclear imaging) and invasive techniques (arterial stimulation with venous sampling) can be used. Debulking procedures (surgery, radiofrequency ablation, embolization/chemoembolization and liver transplantation) and/or medical treatment (chemotherapy, biotherapy and peptide receptor radionuclide therapy) are the options available for the treatment of EPTs. Understanding the molecular events underlying the pathobiology of EPTs will aid the development of more accurate diagnostic/prognostic markers and give guidance for improved therapeutic modalities.

Endocrine tumors of the pancreas

Neuroendocrine tumors of the pancreas are rare neoplasms of the heterogeneous group of neuroendocrine gastroenteropancreatic tumors that originate from totipotential stem cells or preexisting endocrine cells within the pancreas. Most neuroendocrine tumors of the pancreas are benign or show an indolent course of disease.A subset of them shows a very aggressive behavior, becomes highly malignant, and metastasizes early with life-limiting consequences. An effective disease-management includes the diagnostic approach with hormonal testing and localization and surgical treatment with histologic classification in combination with biotherapy, chemotherapy, or therapy with radionucleotides, de-pending on the individual behavior of the tumor. The primary goal is the improvement of symptoms leading to an acceptable quality of life in the individual patient.

Molecular Evidence for Independent Origin of Multifocal Neuroendocrine Tumors of the Enteropancreatic Axis

Neuroendocrine tumors of the enteropancreatic axis are often multifocal. We have investigated whether multifocal intestinal carcinoid tumors and multifocal pancreatic endocrine tumors arise independently or whether they originate from a single clone with subsequent intramural or intrapancreatic spread. Twenty-four cases, including 16 multifocal intestinal carcinoid tumors and eight multifocal pancreatic endocrine tumors, were studied. Genomic DNA samples were prepared from 72 distinct tumor nodules using laser capture microdissection. Loss of heterozygosity (LOH) assays were done using markers for putative tumor suppressor genes located on chromosomes 9p21 (p16), 11q13 (MEN1), 11q23 (SDHD), 16q21, 18q21, and 18q22-23. In addition, X chromosome inactivation analysis was done on the tumors from eight female patients. Twenty-two of 24 (92%) cases showed allelic loss in at least one tumor focus, including 15 of 16 (94%) cases of multifocal carcinoid tumors and 7 of 8 (88%) cases of multifocal pancreatic endocrine tumors. Eleven of 24 (46%) cases exhibited a different LOH pattern for each tumor. Additionally, 9 of 24 (38%) cases showed different LOH patterns among some of the coexisting tumors, whereas other coexisting tumors displayed the same allelic loss pattern. Two of 24 (8%) cases showed the same LOH pattern in every individual tumor. X chromosome inactivation analysis showed a discordant pattern of nonrandom X chromosome inactivation in two of six informative cases and concordant pattern of nonrandom X chromosome inactivation in the four remaining informative cases. Our data suggest that some multifocal neuroendocrine tumors of the enteropancreatic axis arise independently, whereas others originate as a single clone with subsequent local and discontinuous metastasis.

[Surgical treatment of gastric, enteric, and pancreatic endocrine tumors Part 1. Treatment of primary endocrine tumors]

Endocrine tumors (ET) of the digestive tract (formerly called neuroendocrine tumors) are rare. They are classified into two principal types: gastrointestinal ET's (formerly called carcinoid tumors) which are the most common, and pancreaticoduodenal ET's. Functioning ET's secrete polypeptide hormones which cause characteristic hormonal syndromes. The management of ET is multidisciplinary. Poorly-differentiated ET's have a poor prognosis and are treated by chemotherapy. Surgical excision is the only curative treatment of well-differentiated ET's. The surgical goals are to: 1. prolong survival by resecting the primary tumor and any nodal or hepatic metastases, 2. control the symptoms related to hormonal secretion, 3. prevent or treat local complications. The most common sites of gastrointestinal ET's ( carcinoids) are the appendix and the rectum; these are often small (<1 cm), benign, and discovered fortuitously at the time of appendectomy or colonoscopic removal. Ileal ET's, even if small, are malignant, frequently multiple, and complicated in 30-50% of cases by bowel obstruction, mesenteric invasion, or bleeding. The carcinoid syndrome (consisting of abdominal pain, flushing, diarrhea, hypertension, bronchospasm, and right sided cardiac vegetations) is caused by the hypersecretion of serotonin into the systemic circulation; it occurs in 10% of cases and is usually associated with hepatic metastases. More than half of the cases of pancreatic ET are non-functional. They are usually malignant and of advanced stage at diagnosis presenting as a palpable or obstructing mass or as liver metastases. Insulinoma and gastrinoma (cause of the Zollinger-Ellison syndrome) are the most common functional ET's. 80% are sporadic; in these cases, tumor size, location, and malignant potential determine the type of resection which may vary from a simple enucleation to a formal pancreatectomy. In 10-20% of cases, pancreaticoduodenal ET presents in the setting of multiple endocrine neoplasia (NEM type I), an autosomal-dominant genetic disease with multifocal endocrine involvement of the pituitary, parathyroid, pancreas, and adrenal glands. For insulinoma with NEM-I, enucleation of lesions in the pancreatic head plus a caudal pancreatectomy is the most appropriate procedure. For gastrinoma with NEM-I, the benefit of surgical resection for tumors less than 2-3 cm in size is not clear. The lesions are frequently small, multiple, and widespread and recurrence is frequent after excision. The long-term prognosis is nevertheless fairly good. But the eventual development of liver metastases which are the most common cause of mortality still argues for an aggressive surgical approach in the early stages of the disease.

[Pancreatic panniculitis with intraductal carcinoid tumor of the pancreas divisum]

BACKGROUND

The association of pancreatic diseases with panniculitis are rare. Various pancreatic diseases are described with panniculitis of which most frequent are pancreatitis and acinar cell carcinoma. We report a case of an acute nodular panniculitis whose etiologic assessment allow of discover an intraductal carcinoid tumour on a pancreas divisum.

CASE REPORT

A 45 year-old woman without notable medico-surgical history had suddenly presented with multiple cutaneous erythematous nodules on the legs associated with moderates arthralgia in the wrists and the ankles. There were no other clinical manifestations. Results of laboratory tests and chest X-ray were normal. Histologic exploration showed a centrolobular fat necrosis and suggestive pancreatic disease was confirmed by an increase in serum pancreatic enzymes. Ultrasound study and computerized tomography of the abdomen was without notable anomaly. Endoscopic ultrasound study of the pancreas and magnetic resonance imaging showed moderate distention of the pancreatic duct. Endoscopic retrograde cholangiopancreatography highlighted a small tumor in the accessory duct orifice of the pancreas divisum. Immunohistological study of tumor's biopsy showed a carcinoid tumor.

DISCUSSION

To our knowledge, this observation describes the first case of nodular panniculitis associated with carcinoid tumor of the pancreas. The detection of this tumor at an early stage, revealed by cutaneous fat necrosis, is probably due to the unusual anatomic site, on the accessory papilla of the pancreas divisum.

The diagnosis and medical management of advanced neuroendocrine tumors

Neuroendocrine tumors (NETs) constitute a heterogeneous group of neoplasms that originate from endocrine glands such as the pituitary, the parathyroids, and the (neuroendocrine) adrenal, as well as endocrine islets within glandular tissue (thyroid or pancreatic) and cells dispersed between exocrine cells, such as endocrine cells of the digestive (gastroenteropancreatic) and respiratory tracts. Conventionally, NETs may present with a wide variety of functional or nonfunctional endocrine syndromes and may be familial and have other associated tumors. Assessment of specific or general tumor markers offers high sensitivity in establishing the diagnosis and can also have prognostic significance. Imaging modalities include endoscopic ultrasonography, computed tomography and magnetic resonance imaging, and particularly, scintigraphy with somatostatin analogs and metaiodobenzylguanidine. Successful treatment of disseminated NETs requires a multimodal approach; radical tumor surgery may be curative but is rarely possible. Well-differentiated and slow-growing gastroenteropancreatic tumors should be treated with somatostatin analogs or alpha-interferon, with chemotherapy being reserved for poorly differentiated and progressive tumors. Therapy with radionuclides may be used for tumors exhibiting uptake to a diagnostic scan, either after surgery to eradicate microscopic residual disease or later if conventional treatment or biotherapy fails. Maintenance of the quality of life should be a priority, particularly because patients with disseminated disease may experience prolonged survival.

Neuroendocrine markers in adenocarcinomas: an investigation of 356 cases

AIM: To investigate the incidence of neuroendocrine (NE) cells and their hormone products in adenocarcinomas and evaluate their significance in clinical pathology and prognosis.

METHODS: By using tissue sectioning and immunocyto-chemistry, 356 cases of adenocarcinomas were studied to examine the presence of chromorgranin and polypeptide hormones in adenocarcinoma samples from our hospital.

RESULTS: The positive rate of NE cells and hormone products was 41.5% (54/130) and 59.3% (32/54), respectively in large intestinal adenocarcinoma cases; 39.6% (38/96) and 36.8% (14/38), respectively in gastric cancer cases; 38.1% (8/21) and 50.0% (4/8), respectively in prostatic cancer cases; 21.0% (17/81) and 17.6% (3/17), respectively in breasr cancer cases; 17.9% (5/28) and 60.0% (3/5), respectively in pancreatic cancer cases. Among carcinomas of large intestine, pancreas and breast, the highly differentiated NE cell numbers were higher than the poorly differentiated NE cell numbers; while the gastric carcinoma cases had more poorly differentiated NE cells than highly differentiated NE cells. The higher detection rate of NE cells and their hormone products, the higher 5-year survival rate among the large intestine cancer cases.

CONCLUSION: Close correlation was observed between NE cells and their hormone products with the cancer differentiations. For colorectal carcinomas, there is a close correlation of the presence of NE cells and their hormone products with the tumor staging and prognosis.

Carcinoid of the pancreas

Pancreatic carcinoids are very rare and usually have a poor prognosis. We describe a case of a pancreatic carcinoid with liver micrometastases in a female of 54 years of age in whom the tumor was without pronounced symptoms apart from rare episodes of flushing. The patient had been treated since November 1995 with the somatostatin analogue octreotide 200 micrograms twice daily for the first 2 years, with the long-acting analogue lanreotide 30 mg every 10 days for the following year, and then with octreotide LAR 20 mg every 28 days until the present. The flushing episodes disappeared completely, and the patient was well. Moreover, the dimensions of the tumor and the liver micrometastases remained stable during the observation period. As far as we known, this is the first case of a pancreatic carcinoid treated successfully with somatostatin analogues and having a satisfactory prognosis.

[Pancreatic carcinoid]

Carcinoid tumours arise from argentaffine cells or from a primitive stem cells which may differentiate into anyone of a variety of adult endocrine-secreting cells. Carcinoid tumour of the pancreas is a very rare tumour with less than 50 cases reported in world literature. In literature it is denoted "pancreatic serotoninoma" or "serotonin-producing pancreatic tumour". Due to its rarity the tumour is an unusual cause of carcinoid syndrome. As the carcinoid tumour of the pancreas does not always causes carcinoid syndrome its absence does not necessarily exclude the existence of the tumour. The tumour is frequently malignant. Over 50% of patients have metastases at the time of surgery. This is the reason why radical surgery is not possible in a number of patients. Excisional surgery offers the best chance for recovery or long term survival. We report on a 57-year-old woman with carcinoid syndrome caused by malignant carcinoid tumour of the head of the pancreas without liver or other distant metastases; it was successfully excised with pylorus preserving cephalic duodenopancreatectomy (after Longmire-Traverso) and radical lymphadenectomy. The diagnosis was established on the basis of histologic and immunohistochemical findings. The patient is symptom free for more than eight months.

The pigmented "black" neuroendocrine tumor of the pancreas: a question of origin

BACKGROUND

Pigmented neoplasms are extremely rare in the pancreas, and, when black pigment is identified, it often suggests the diagnosis of metastatic melanoma. The authors describe two patients with pigmented "black" neuroendocrine tumors of the pancreas. One patient had an incidental (0.5 cm) finding, and the second patient had a well-demarcated, 4.5-cm mass identified by computerized tomography that was consistent with an islet cell tumor.

METHODS

The two neoplasms were resected surgically and studied by light microscopy using hematoxylin and eosin (H&E), Fontana-Masson, and iron stains. The neoplasms were examined immunohistochemically, and ultrastructural analysis was performed.

RESULTS

H&E stains revealed nests of well-differentiated cells with small, round, centrally placed nuclei. The cytoplasm of the neoplastic cells was pink and granular and contained abundant brown-black pigment. Angiolymphatic and perineural invasion were identified in the larger neoplasm. Both neoplasms demonstrated a positive reaction with a Fontana-Masson stain, which was susceptible to bleaching, and a negative reaction to an iron stain. Immunohistochemical stains showed that neoplastic cells expressed chromogranin and synaptophysin but did not express HMB-45, S-100 protein, glucagon, or insulin. Ultrastructural examination revealed regular neurosecretory granules (100-150 nm) and large, irregularly shaped, electron-dense granules with small lipid inclusions consistent with lipofuscin.

CONCLUSIONS

These pigmented pancreatic neoplasms are similar histologically and radiographically to the "black adenoma" of the adrenal gland. It is important to recognize these tumors, because they may mimic metastatic melanoma.

[Endocrine tumors of the duodenum and pancreas: "prerequisites", imaging, and intraoperative detection]

Non-secreting pancreatic neuroendocrine tumors and diarrheogenic tumors are usually bulky and easy to recognize thanks to somatostatin-receptor scintigraphy and hormonal dosages. The real difficulty concerns insulinomas and particularly gastrinomas, which are found at the level of the duodenum and can be very small. Diagnosis is based on biological examinations, and the search for MEN I must be done systematically. Their localization is based on two essential and noninvasive exams: echoendoscopy and somatostatin-receptor imaging, though the surgeon's skill in the operative field, aided by an intraoperioperative echography, is indispensable. Surgical treatment of insulinomas gives excellent results. However, for sporadic gastrinomas, there was only a 34% recovery rate, and still less for MEN I gastrinomas.

Diagnosis and staging of islet cell tumors of the pancreas

Pancreatic endocrine tumors arise from the amine precursor uptake and decarboxylation (APUD) cells of the pancreas and behave in a different fashion both biologically and clinically from pancreatic adenocarcinoma. Gastrinomas and insulinomas are the two most common pancreatic endocrine tumors. Unlike pancreatic adenocarcinoma, in which tumor stage, resectability, and prognosis are determined by the tumor, nodes, and metastasis (TNM) classification, the prognosis of pancreatic endocrine tumors is determined by the presence of liver but not regional lymph node metastasis. This review focuses predominantly on the different diagnostic tools available to the clinician and the relative merits of each modality. The sensitivities of computed tomography, magnetic resonance imaging, somatostatin receptor scintigraphy, endoscopic ultrasound, and angiography with venous sampling for diagnosing islet cell tumors are compared. A diagnostic algorithm for the management of these tumors is provided at the end of the discussion.

Pancreatic endocrine tumors: recent advances

Pancreatic endocrine tumors (PET's) can be divided on a clinical and pathologic basis into ten classes [insulinomas, gastrinomas (Zollinger-Ellison syndrome), VIPomas (Verner-Morrison syndrome, WDHA, pancreatic cholera), glucagonomas, somatostatinomas, ACTH-releasing tumors (ACTHomas), growth hormone-releasing factor secreting tumors (GRFomas), nonfunctioning or pancreatic polypeptide secreting tumors (non-functioning PET), PET's causing carcinoid syndrome and PET's causing hypercalcemia)]. Recent reports suggest calcitonin-secreting PET's also rarely occur but whether they cause a distinct clinical syndrome is unclear. PET's resemble carcinoid tumors histologically; in their ability to synthesize and frequently secrete multiple peptides such as neuroendocrine cell markers (chromogranins); their biologic behavior and their tumor growth patterns. Both groups of tumors are highly vascular, have high densities of somatostatin receptors and similar tumor localization studies including somatostatin receptor scintigraphy are used for both. PET's, similar to carcinoids causing the carcinoid syndrome, require two separate treatment options be considered: treatment directed against the hormone-excess state and treatment directed against the tumor per se because of their malignant nature. In the last few years there have been advances in tumor diagnosis, localization methods, treatment approaches particularly related to the use of synthetic somatostatin analogues, and the definition of the role of surgical procedures in these diseases. Important other advances include insights into the long-term natural history of PET's particularly from studies of gastrinomas, which allow prognostic factors to be identified and the timing of treatment options to better planned, as well as insights into the molecular basis of these disorders. The latter includes both a description of the molecular basis of the genetic inherited syndromes associated with PET's or carcinoid tumors, as well as an increased understanding of the molecular basis for sporadic PET's or carcinoid tumors. Each of these areas will be briefly highlighted in this presentation.