Loss of Chromosome 18 in Neuroendocrine Tumors of the Small Intestine: The Enigma Remains.

BACKGROUND/AIMS: Neuroendocrine tumors of the small intestine (SI-NETs) exhibit an increasing incidence and high mortality rate. Until now, no fundamental molecular event has been linked to the tumorigenesis and progression of these tumors. Only the loss of chromosome 18 (Chr18) has been shown in up to two thirds of SI-NETs, whereby the significance of this alteration is still not understood. We therefore performed the first comprehensive study to identify Chr18-related events at the genetic, epigenetic and gene/protein expression levels. METHODS: We did expression analysis of all seven putative Chr18-related tumor suppressors by quantitative real-time PCR (qRT-PCR), Western blot and immunohistochemistry. Next-generation exome sequencing and SNP array analysis were performed with five SI-NETs with (partial) loss of Chr18. Finally, we analyzed all microRNAs (miRNAs) located on Chr18 by qRT-PCR, comparing Chr18+/- and Chr18+/+ SI-NETs. RESULTS: Only DCC (deleted in colorectal cancer) revealed loss of/greatly reduced expression in 6/21 cases (29%). No relevant loss of SMAD2, SMAD4, elongin A3 and CABLES was detected. PMAIP1 and maspin were absent at the protein level. Next-generation sequencing did not reveal relevant recurrent somatic mutations on Chr18 either in an exploratory cohort of five SI-NETs, or in a validation cohort (n = 30). SNP array analysis showed no additional losses. The quantitative analysis of all 27 Chr18-related miRNAs revealed no difference in expression between Chr18+/- and Chr18+/+ SI-NETs. CONCLUSION: DCC seems to be the only Chr18-related tumor suppressor affected by the monoallelic loss of Chr18 resulting in a loss of DCC protein expression in one third of SI-NETs. No additional genetic or epigenetic alterations were present on Chr18.

Incidence of preclinical manifestations of mantle cell lymphoma and mantle cell lymphoma in situ in reactive lymphoid tissues.

Recently, the occurrence of cyclin D1-positive B cells with mantle cell lymphoma phenotype in the inner mantle zones of morphologically inconspicuous lymph nodes has been described and termed mantle cell lymphoma 'in situ'. Prevalence and clinical significance of this lesion and related minimal mantle cell lymphoma infiltrates in reactive lymphoid tissues of healthy individuals, and of mantle cell lymphoma patients are unknown. All 1292 reactive lymph nodes from unselected consecutive surgical specimens of 131 patients without a history of lymphoma obtained over a 3-month period were stained for cyclin D1. In addition, all morphologically reactive lymph nodes and benign-appearing extranodal lymphoid infiltrates of patients diagnosed with mantle cell lymphoma in the years 2000-2011 were studied. Samples predating the lymphoma diagnosis for at least 2 months were available from 37/423 (9%) patients. A mantle cell lymphoma 'in situ' was not identified in any of the two groups. However, in four patients with subsequent mantle cell lymphoma diagnosis, an early manifestation of mantle cell lymphoma was detected retrospectively, antedating the lymphoma diagnosis for 2-86 months. In six mantle cell lymphoma patients, only small groups of cyclin D1-positive cells in morphologically reactive extranodal infiltrates were detected >2 months before the diagnosis of mantle cell lymphoma (range 3-59 months). Mantle cell lymphoma 'in situ' is an extremely rare phenomenon in morphologically reactive lymph nodes, in line with the low prevalence of t(11;14)-positive cells described in the peripheral blood of a healthy population. In mantle cell lymphoma patients, however, immunohistochemically detectable infiltrates of mantle cell lymphoma cells antedating the lymphoma diagnosis were found in a significant proportion of cases (10/37=27%). These consisted either of early mantle cell lymphoma with mantle zone growth pattern, or small extranodal accumulations of cyclin D1+ cells, whereas typical mantle cell lymphoma 'in situ' was not detected.

Prevalence of follicular lymphoma in situ in consecutively analysed reactive lymph nodes.

AIMS: Follicular lymphoma (FL) in situ is defined as strongly bcl-2-positive B cells in germinal centres of morphologically inconspicuous lymph nodes. The prevalence and biological and clinical significance of this lesion are still not clear. Therefore we aimed at the detection of the prevalence of this phenomenon in an unselected series of lymph nodes, as a surrogate for the normal population. METHODS AND RESULTS: All 1294 reactive lymph nodes from unselected consecutive surgical specimens of 132 patients in a 3-month period were stained for bcl-2 protein. The t(14;18) translocation was investigated by fluorescence in-situ hybridization (FISH) analysis. FL in situ was identified in 22 lymph nodes in 3/132 patients (2.3%) without evidence or history of malignant lymphoma, and confirmed by detection of the t(14;18) translocation by FISH. Interestingly, in one patient, a lymph node excised 2 years before also contained FL in situ. CONCLUSIONS: We found a prevalence of 2.3% for FL in situ lesions in an unselected series of lymph nodes, as a surrogate for the normal population. Taking into account the incidence of manifest FL, the risk of progression of this lesion is probably limited. It can be speculated that some FL in situ lesions do indeed represent an early step in lymphomagenesis, whereas others persist without further progression to overt FL. The underlying mechanisms, however, remain to be elucidated.

Glucagon cell adenomatosis: a newly recognized disease of the endocrine pancreas.

BACKGROUND: Glucagon-producing tumors are either solitary neoplasms of the pancreas, occasionally associated with a glucagonoma syndrome, or multiple neoplasms associated with multiple endocrine neoplasia type 1 (MEN1). We observed a previously undescribed multicentric glucagon-producing tumor disease that is not related to MEN1. METHODS: Pancreatic tissue from four patients showing multiple neuroendocrine microadenomas and in two cases also macrotumors were screened for hormones using immunohistochemical and morphometric methods. MEN1, von Hippel-Lindau, and p27 germ line and somatic mutation analysis was performed. Deletion of MEN1 (11q13), von Hippel-Lindau (3p25), and the centromere 11 and 3 gene locus was determined by fluorescence in situ hybridization. DNA copy number changes were studied using array comparative genomic hybridization. RESULTS: The pancreatic tissue from the four patients contained more than 870 microadenomas and 10 macrotumors, all of which expressed exclusively glucagon and none of which showed evidence of malignancy. In addition, many islets were unusually large and showed glucagon cell hyperplasia. There was no clinical or molecular evidence of any hereditary tumor disease, and changes in the MEN1 gene were only seen in individual tumors. Array comparative genomic hybridization of one macrotumor and 20 pooled microadenomas revealed a homogeneous diploid chromosome set. CONCLUSIONS: The findings are sufficiently distinctive to suggest a new neoplastic disease of the endocrine pancreas that we recommend calling glucagon cell adenomatosis. Clinically, this disease may be an incidental finding, or it may lead to a glucagonoma syndrome.

Investigation of the colorectal cancer susceptibility region on chromosome 8q24.21 in a large German case-control sample.

Human chromosome 8q24.21 has been implicated as a susceptibility region for colorectal cancer (CRC) as a result of genome-wide association and candidate gene studies. To assess the impact of molecular variants at 8q24.21 upon the CRC risk of German individuals and to refine the disease-associated region, a total of 2,713 patients with operated CRC (median age at diagnosis: 63 years) were compared with 2,718 sex-matched control individuals (median age at inclusion: 65 years). Information on microsatellite instability in tumors was available for 901 patients. Association analysis of SNPs rs10505477 and rs6983267 yielded allelic p-values of 1.42 x 10(-7) and 2.57 x 10(-7), respectively. For both polymorphisms, the odds ratio was estimated to be 1.50 (95% CI: 1.29-1.75) under a recessive disease model. The strongest candidate interval, outside of which significance dropped by more than 4 orders of magnitude, was delineated by SNPs rs10505477 and rs7014346 and comprised 17 kb. In a subgroup analysis, the disease association was found to be more pronounced in MSI-stable tumors (odds ratio: 1.71). Our study confirms the role of genetic variation at 8q24.21 as a risk factor for CRC and localizes the corresponding susceptibility gene to a 17 kb candidate region.

Somatostatin-producing neuroendocrine tumors of the duodenum and pancreas: incidence, types, biological behavior, association with inherited syndromes, and functional activity.

Somatostatin-producing neuroendocrine tumors (SOM-NETs) of the duodenum and pancreas appear to be heterogeneous. To determine their clinicopathological profiles, respective data were analyzed on a series of 82 duodenal and 541 pancreatic NETs. In addition, the clinical records of 821 patients with duodenal or pancreatic NETs were reviewed for evidence of a somatostatinoma syndrome. Predominant or exclusive expression of somatostatin was found in 21 (26%) duodenal and 21 (4%) pancreatic NETs. They were classified as sporadic (n=31) or neurofibromatosis type 1 (NF1)-associated duodenal NETs (n=3), gangliocytic paragangliomas (GCPGs; n=6), or poorly differentiated neuroendocrine carcinomas (pdNECs; n=2). In addition, five duodenal and four pancreatic SOM-NETs were found in five patients with multiple endocrine neoplasia type 1 (MEN1). Metastases occurred in 13 (43%) patients with sporadic or NF1-associated SOM-NETs, but in none of the duodenal or pancreatic MEN1-associated SOM-NETs or GCPGs. Sporadic advanced (stage IV) SOM-NETs were more commonly detected in the pancreas than in the duodenum. None of the patients (including the 821 patients for whom only the clinical records were reviewed) fulfilled the criteria of a somatostatinoma syndrome. Our data show that somatostatin expression is not only seen in sporadic NETs but may also occur in GCPGs, pdNECs, and hereditary NETs. Surgical treatment is effective in most duodenal and many pancreatic SOM-NETs. MEN1-associated SOM-NETs and GCPGs follow a benign course, while somatostatin-producing pdNECs are aggressive neoplasms. The occurrence of the so-called somatostatinoma syndrome appears to be extremely uncommon.

Multiple endocrine neoplasia type 1 (MEN1): loss of one MEN1 allele in tumors and monohormonal endocrine cell clusters but not in islet hyperplasia of the pancreas.

CONTEXT: The occurrence of multiple small pancreatic endocrine tumors in patients suffering from multiple endocrine neoplasia type 1 (MEN1) represents a unique possibility to study early neoplasms and their potential precursor lesions. To date, it is unknown whether small islet-like endocrine cell clusters found in MEN1 patients are neoplastic or rather hyperplastic. It is also unclear whether microadenomas develop from islets. DESIGN: We hypothesized that monohormonal endocrine cell clusters observed in MEN1 patients are small neoplasms with loss of heterozygosity of the MEN1 locus. Using a technique combining fluorescence in situ hybridization of the MEN1 locus and the centromeric region of chromosome 11q with hormone immunostaining, we examined resection specimens from four MEN1 patients. We focused our investigations on the following: 1) typical microadenomas; 2) monohormonal endocrine cell clusters; 3) endocrine and exocrine structures entrapped in microadenomas; and 4) morphologically normal islets. RESULTS: Loss of one MEN1 allele was found in all 27 microadenomas and 19 of 20 (95%) monohormonal endocrine cell clusters. By contrast, it was absent in islets and ductal or acinar structures. Our results indicate that monohormonal endocrine cell clusters represent a minute form of microadenomas. CONCLUSION: The frequent presence of single nonneoplastic insulin cells in microadenomas and the occurrence of microadenomas in islets suggest an islet origin of microadenomas. Islet hyperplasia does not seem to be an obligatory stage in pancreatic MEN1-associated tumor development.

Hereditary neuroendocrine tumors of the gastroenteropancreatic system.

Approximately 5-10% of neuroendocrine tumors (NETs) of the gastroenteropancreatic system (GEP) have a hereditary background. The known inherited syndromes include multiple endocrine neoplasia type 1, neurofibromatosis type 1, von Hippel-Lindau disease, and the tuberous sclerosis complex. This review discusses for each of these syndromes the: (1) involved genes and specific types of mutations, (2) disease prevalence and penetrance, (3) affected neuroendocrine tissues and related clinical syndromes, (4) special morphological features of NETs and their putative precursor lesions. In addition, GEP-NETs clustering in individual families or associated with other malignancies without known genetic background are discussed.

Sporadic versus hereditary gastrinomas of the duodenum and pancreas: distinct clinico-pathological and epidemiological features.

Gastrinomas are defined as gastrin secreting tumors that are associated with Zollinger-Ellison syndrome (ZES). ZES is characterized by elevated fasting gastrin serum levels, positive secretin stimulation test and clinical symptoms such as recurrent peptic ulcer disease, gastroesophageal reflux disease and occasional diarrhea. Genetically, nonhereditary (sporadic) gastrinomas are distinguished from hereditary gastrinomas, which are associated with multiple endocrine neoplasia type 1 (MEN1) syndrome. In general, duodenal gastrinomas are small and solitary if they are sporadic and multiple as well as hereditary. The sporadic gastrinomas occur in the duodenum or in the pancreas while the hereditary gastrinomas almost all occur in the duodenum. Our series of 77 sporadic duodenal neuroendocrine tumors (NETs) includes 18 patients (23.4%) with gastrinomas and ZES. Of 535 sporadic NETs in the pancreas collected from the NET archives of the departments of pathology in Zurich, Switzerland, and Kiel, Germany, 24 patients (4.5%) suffered from sporadic pancreatic gastrinomas and ZES. These NETs have to be distinguished from tumors with immunohistochemical positivity for gastrin but without evidence of ZES. An additional 19 patients suffered from MEN1 and ZES. These patients showed exclusively duodenal gastrinomas, but not pancreatic gastrinomas. The prognosis of sporadic and MEN1-associated duodenal gastrinomas is better than that of pancreatic gastrinomas, since they progress slowly to liver metastasis. In summary, sporadic and MEN1-associated gastrinomas in the duodenum and pancreas show different clinico-pathological and genetic features. The incidence of sporadic duodenal gastrin-producing tumors is increasing, possibly due to optimized diagnostic procedures. In contrast, pancreatic MEN1-associated gastrinomas seem to be extremely rare. A considerable subset of tumors with immunohistochemical expression of gastrin but without evidence of ZES should be designated as functionally inactive NETs expressing gastrin, but not as gastrinomas.

Glucagon cell hyperplasia and neoplasia with and without glucagon receptor mutations.

CONTEXT: Glucagon cell adenomatosis (GCA) was recently recognized as a multifocal hyperplastic and neoplastic disease of the glucagon cells unrelated to multiple endocrine neoplasia type 1 and von-Hippel-Lindau disease. OBJECTIVE: The study focused on the molecular analysis of the glucagon receptor (GCGR) gene in GCA and a description of the clinicopathological features of GCA with and without GCGR mutations. DESIGN: Pancreatic tissues from patients showing multiple glucagon cell tumors were morphologically characterized and macro- or microdissected. All exons of the GCGR gene were analyzed for mutations by Sanger and next-generation sequencing. Genotyping for all detected GCGR variants was performed in 2560 healthy individuals. PATIENTS: Six patients with GCA, and the parents of one patient were included in the study. MAIN OUTCOME MEASURES: The main outcome measures were the correlations between the patients' GCGR mutation status and the respective clinicopathological data. RESULTS: GCGR germline mutations were found in three of six patients. Patient 1 harbored a homozygous stop mutation. This patient's parents showed an identical but heterozygous GCGR mutation. Patient 2 had two different heterozygous point mutations leading each to premature stop codons. Patient 3 exhibited two homozygous missense mutations. No GCGR mutations were identified in the three other patients and in a large cohort of healthy subjects. The patients harboring GCGR mutations exhibited a greater number of tumors and larger tumors than patients with wild-type GCGR. One of the patients with wild-type GCGR showed lymph node micrometastases. CONCLUSIONS: GCA with GCGR germline mutations seems to follow an autosomal-recessive trait. By interrupting the GCGR signaling pathways GCGR mutations probably cause GCA via glucagon cell hyperplasia. GCA also occurs in patients without GCGR mutations, but seems to be associated with fewer and smaller tumors.

Insulinomatosis: a multicentric insulinoma disease that frequently causes early recurrent hyperinsulinemic hypoglycemia.

BACKGROUND: Multicentric insulinoma disease was characterized with regard to its histopathology, multiple endocrine neoplasia type 1 (MEN1) status, precursor lesions, and the risk of hyperinsulinemic hypoglycemia recurrence. METHODS: Fourteen patients with multicentric insulinoma disease were compared with 267 patients with sporadic and familial insulinomas. The tumors were classified according to the World Health Organization (WHO) criteria. The MEN1 status was defined clinically and by germline mutation analysis. Detection of the MEN1 gene locus was performed using fluorescence in situ hybridization. The surgical interventions and the duration of disease-free survival were recorded. RESULTS: Fourteen patients (5%) without evidence of MEN1 showed 53 macrotumors and 285 microtumors expressing exclusively insulin. In addition, they had small proliferative insulin-expressing monohormonal endocrine cell clusters (IMECCs). No allelic loss of the MEN1 locus was detected in 64 tumors. All but one patient had benign disease. Recurrent hypoglycemia occurred in 6/14 patients (11 recurrences; mean time to relapse 8.4 y). Thirteen patients with MEN1 (4.6%) showed 41 insulinomas and 133 tumors expressing islet hormones other than insulin. IMECCs were not detected. Allelic loss of the MEN1 locus was found in 17/19 insulinomas. Recurrent hypoglycemia occurred in 4/13 patients (4 recurrences; mean time to relapse 14.5 y). Solitary insulinomas were found in 254/281 patients (90.4%). IMECCs were absent. There was no recurrent hypoglycemia in 84 patients with benign insulinomas. CONCLUSIONS: Insulinomatosis is characterized by the synchronous and metachronous occurrence of insulinomas, multiple insulinoma precursor lesions, and rare development of metastases, but common recurrent hypoglycemia. This disease differs from solitary sporadic and MEN1-associated insulinomas.

Extraabdominal malposition of the gallbladder.

Anomalies of the biliary system are rare. Anomalies of the gallbladder and anomalies of the bile ducts are distinguished. We observed a newborn with a gallbladder in an extraabdominal malposition, an anomaly that has not been previously described. Ultrasonography revealed a cystic structure with a ductlike connection with the interior surface of the liver and connecting blood vessels. On the bottom side of the liver, there was no orthotopic gallbladder. As the nature of this lesion could not be definitely clarified, an explorative laparotomy was performed. Histologic examination established the diagnosis of an ectopic gallbladder. Malformations of the extrahepatic bile passages are difficult to assess, as only a small percentage of such anomalies produce symptoms. Knowledge of the wide range of possible abnormalities in position, shape, and number of the gallbladder can help in cases where the diagnosis is unclear. Abnormally positioned gallbladders should be removed. The possibility of an ectopic gallbladder must be kept in mind when a suspicious cystic area is encountered in an atypical location, when the gallbladder is not seen in its normal location, or the preoperative diagnostic workup does not confirm the typical clinical symptoms of gallbladder disease.

Primary lymph node gastrinoma or occult duodenal microgastrinoma with lymph node metastases in a MEN1 patient: the need for a systematic search for the primary tumor.

Gastrinoma tissue has been found frequently in lymph nodes located near the duodenum without a known primary tumor. Therefore, it has been suggested that a primary lymph node gastrinoma exists. We report on a 38-year-old woman suffering from multiple endocrine neoplasia type 1 (MEN1) confirmed by menin gene mutation analysis. MEN1 disease started with primary hyperparathyroidism followed by Cushing disease, the detection of tumors of the pituitary, adrenal cortex, and the pancreas and also an elevated serum gastrin level. An octreotide scan revealed 4 tumors in the upper abdomen. A selective arterial calcium stimulation test located the source of the hypergastrinemia to the area of the gastroduodenal and the superior mesenteric arteries. Total pancreatoduodenectomy was performed and conventional histopathologic examination revealed a well-differentiated cystic neuroendocrine tumor of the pancreas expressing glucagon and accompanied by several microadenomas. In addition, 3 suprapancreatic lymph nodes with gastrin-positive endocrine tissue were found. None of the pancreatic microadenomas expressed gastrin and no duodenal endocrine tumor was found despite careful macroscopic examination. Only after complete embedding of the duodenal and pancreatic tissue in 65 paraffin blocks, 2 microgastrinomas (0.45 and 0.8 mm in diameter) were identified in the duodenum. It is concluded that duodenal gastrinomas that give rise to lymph node metastases may be so tiny that they are easily overlooked in a routine examination and that systematic tissue monitoring is required to identify them.