[Neuroendocrine neoplasms : Two families with distinct features unified in one classification (German version)]. / Neuroendokrine Neoplasien : Zwei Familien mit sehr unterschiedlichen Charakteristika vereint in einer Klassifikation.

All neuroendocrine neoplasms (NENs) are characterized by the expression of synaptophysin and chromogranin A (or B). Yet, they are not a homogeneous group of tumors. Paradigmatic for these tumors are the NENs of the gastroenteropancreatic (GEP) system. Two NEN families can be distinguished: predominantly well differentiated and low-proliferative NENs, called neuroendocrine tumors (NET), and poorly differentiated and high-proliferative NENs, called neuroendocrine carcinomas (NECs). Based on their proliferative activity, GEP NETs are further classified into G1, G2, and G3 tumors. NECs are per definition G3 carcinomas. The morphological NEN dichotomy is supported by differences in epidemiology, genetics, clinics, and prognosis, and potentially has its cause originating from different progenitor cells. Genetically, NECs are distinguished by TP53 and RB1 alterations, which are lacking in NETs and are helpful in the distinction of NETs from NECs. Comparison of the GEP NEN WHO classification with extragastroenteropancreatic NEN classifications commonly reveal differences in terminology and categorization. In addition, they lack a grading system. However, common to all NEN classifications is the recognition of two tumor families differing in histological differentiation and prognosis. This allows the construction of a uniform classification frame for all NENs.

[Neuroendocrine neoplasms of the head and neck]. / Neuroendokrine Neoplasien der Kopf-Hals-Region.

Common to all neuroendocrine neoplasms (NENs), irrespective of their site of origin, is the expression of synaptophysin and chromogranin A. NENs of the head and neck region derive either from epithelial or neural/neuroectodermal tissues. The epithelial-type NENs express cytokeratins and include the well-differentiated typical and atypical carcinoids (also called low- and intermediate-grade neuroendocrine carcinomas by WHO), the poorly differentiated high-grade neuroendocrine carcinomas of small and large cell type and the mixed neuroendocrine-nonneuroendocrine neoplasms. The neural-neuroectodermal-type NENs comprise olfactory neuroblastoma and paraganglioma, each of them with distinct clinicopathological characteristics. Olfactory neuroblastomas show a spectrum of histologic differentiation and are prognostically classified by Hyams grading. Paragangliomas often occur multiple and show a familial background. Most head and neck NENs occur in the upper respiratory system. Their diagnosis follows the general guidelines for NENs, focusing on immunohistochemical profiling. Molecular examinations are so far only required in individual cases.

Refinement of screening for familial pancreatic cancer.

OBJECTIVE: Surveillance programmes are recommended for individuals at risk (IAR) of familial pancreatic cancer (FPC) to detect early pancreatic cancer (pancreatic ductal adenocarcinoma, PDAC). However, the age to begin screening and the optimal screening protocol remain to be determined. METHODS: IAR from non-CDKN2A FPC families underwent annual screening by MRI with endoscopic ultrasonography (EUS) in board-approved prospective screening programmes at three tertiary referral centres. The diagnostic yield according to age and different screening protocols was analysed. RESULTS: 253 IAR with a median age of 48 (25-81) years underwent screening with a median of 3 (1-11) screening visits during a median follow-up of 28 (1-152) months. 134 (53%) IAR revealed pancreatic lesions on imaging, mostly cystic (94%), on baseline or follow-up screening. Lesions were significantly more often identified in IAR above the age of 45 years (p<0.0001). In 21 IAR who underwent surgery, no significant lesions (PDAC, pancreatic intraepithelial neoplasia (PanIN) 3 lesions, high-grade intraductal papillary mucinous neoplasia (IPMN)) were detected before the age of 50 years. Potentially relevant lesions (multifocal PanIN2 lesions, low/moderate-grade branch-duct IPMNs) occurred also significantly more often after the age of 50 years (13 vs 2, p<0.0004). The diagnostic yield of potentially relevant lesions was not different between screening protocols using annual MRI with EUS (n=98) or annual MRI with EUS every 3rd year (n=198) and between IAR screened at intervals of 12 months (n=180) or IAR that decided to be screened at ≥24 months intervals (n=30). CONCLUSIONS: It appears safe to start screening for PDAC in IAR of non-CDKN2a FPC families at the age of 50 years. MRI-based screening supplemented by EUS at baseline and every 3rd year or when changes in MRI occur appears to be efficient.

[Insulitis in type 1 diabetes]. / Insulitis des Typ-1-Diabetes.

Insulitis is considered to be the key morphological lesion of type 1 diabetes mellitus (T1DM) for which the diagnostic criteria were recently defined. From the immunophenotype of the lymphocytic infiltration, its frequency and extent during the course of T1DM and the presence of autoantibodies against beta cell proteins, it has been deduced that T1DM is a chronic autoimmune disease leading to gradual destruction of the insulin-producing cells of the islets of Langerhans in the pancreas, profound insulin deficiency and chronic hyperglycemia. This review article presents the morphological findings that support this hypothesis and addresses questions that need to be answered in order to further clarify the pathogenesis and to develop specific treatment options.

[Histopathology of IgG4-related disease]. / Histopathologie der IgG4-RD.

At an international consensus conference in 2011, multifocal chronic fibrosing inflammatory processes, which are associated with elevated IgG4 serum levels and/or tissue infiltration with IgG4 positive plasma cells, were recognized as a distinct disease entity called IgG4-related disease (IgG4-RD). As IgG4-RD responds well to steroid treatment but imitates a tumor in many organs, particularly in the pancreas, a biopsy for confirmation of the diagnosis is often warranted. The histological criteria for IgG4-RD as defined in 2011 are based on the following main features: 1) dense lymphoplasmacytic infiltrate, 2) storiform fibrosis and 3) obliterative phlebitis. The diagnosis is further supported by immunohistochemical demonstration of an increased infiltration of IgG4-positive plasma cells and an elevated IgG4/IgG ratio. The morphological criteria of IgG4-RD are in most cases detectable in biopsies and can significantly contribute to the diagnosis of this disease, in concert with clinical, serological (elevated serum IgG4 level) and radiological features.

[Neoplasms of the disseminated neuroendocrine cell system of the gastrointestinal tract]. / Neoplasien des disseminierten neuroendokrinen Zellsystems des Gastrointestinaltrakts.

The classification of neuroendocrine neoplasms (NEN) of the gastrointestinal tract and also the pancreas is based on the World Health Organization (WHO) classification from 2010, the site-related TNM stage classification and the clinicopathological characterization. This allows a classification of NEN that is adapted to the individual patient, is of high prognostic relevance and serves the needs of an adequate treatment. This article summarizes the current knowledge on the clinical pathology of gastrointestinal NEN, in order to enable a rapid diagnostic orientation.

[Classification and malignant potential of pancreatic cystic tumors]. / Klassifikation und malignes Potenzial der zystischen Pankreastumoren.

Cystic lesions of the pancreas are increasingly diagnosed with a reported prevalence of 10 % in 70-year-old individuals. Despite their broad spectrum, most resected cystic lesions can be attributed to one of the following entities: intraductal papillary mucinous neoplasms (IPMN), mucinous cystic neoplasms (MCN), serous cystic neoplasms (SCN), neuroendocrine cystic tumors (NECT), and solid pseudopapillary neoplasms (SPN). Among them, IPMN and MCN represent precursors of ductal adenocarcinoma, NECT and SPN are low-grade, potentially malignant lesions, and SCN are usually benign. Due to the not negligible morbidity and mortality rates in pancreatic surgery, even in highly specialized centers, an interdisciplinary preoperative stratification of pancreatic cystic lesions into high- and low-risk tumors is necessary in order to accurately select those cases that need to undergo immediate resection. The role of the pathologist is fundamental in both the preoperative assessment and in the postoperative classification, which determines prognosis, further treatment, and follow-up.

[Neuroendocrine neoplasms of the distal jejunum and ileum]. / Neuroendokrine Neoplasien des distalen Jejunums und Ileums.

Neuroendocrine neoplasms (NEN) of the distal jejunum and ileum derive from serotonin-producing enterochromaffin (EC) cells. Due to their low proliferation rate and their infiltrative growth, they are often discovered at an advanced disease stage when metastasis has already occurred. The biology of these tumours is different from other NEN of the digestive tract. In order to standardise and improve diagnosis and therapy, the guidelines for the diagnosis and clinical management of jejuno-ileal NEN as well as for the management of patients with liver and other distant metastases from NEN were revised by the European Neuroendocrine Tumour Society (ENETS) in 2012. This review focuses on aspects relevant for surgical pathology.

Dipeptidase 1 (DPEP1) is a marker for the transition from low-grade to high-grade intraepithelial neoplasia and an adverse prognostic factor in colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of cancer-related deaths worldwide. Improvements in the understanding of its molecular mechanism and the characterisation of CRC-specific biomarkers facilitating early detection are considered to increase overall survival. METHODS: A meta-analysis of microarray and Serial Analysis of Gene Expression (SAGE) has been performed to identify differentially regulated genes in CRC. Dipeptidase 1 (DPEP1/MDP/RDP) and Syntenin-2 (SDCBP2/SITAC18) were found to be differentially expressed in tumour tissue compared with normal mucosa. Expression of DPEP1 was assessed in a validation set of 87 normal mucosa samples, 20 hyperplastic polyps, 46 CR adenomas with low- and high-grade intraepithelial neoplasia (IEN) and 217 well-documented CRCs by immunohistochemistry and partially by immunoblotting and real-time PCR. RESULTS: Expression of DPEP1 was specifically increased in human CRC tissue samples compared with normal mucosa (P<0.0001, Mann-Whitney U-test), showing a striking upregulation in high-grade compared with low-grade IEN. Furthermore, high DPEP1 expression was found to strongly correlate with histological stage (P<0.0001, chi-square test) as well as localisation (P<0.0001, chi-square test) and has been recognised as an independent adverse prognostic factor, showing significant prognostic values with an ROC (receiver operating characteristic)-AUC of 0.9230. CONCLUSION: Dipeptidase 1 has been identified as an excellent marker of high-grade IEN and CRC, and may thus be applied for screening of early neoplastic lesions and for prognostic stratification.

[IgG4-related systemic disease with autoimmune pancreatitis and lung involvement primarily presenting as pancreatic cancer with pulmonary metastases]. / IgG4-assoziierte Autoimmunpankreatitis und Lungenerkrankung mit der primären, klinischen Präsentation eines pulmonal metastasierten Pankreaskarzinoms.

BACKGROUND: After the first case publication using the term "autoimmune pancreatitis" in 1995 and the successful treatment with steroids we now can distinguish between two clinical und histopathological forms of autoimmune pancreatitis. Type 1 autoimmune pancreatitis (AIP) is usually part of an IgG4-related systemic disease. AIP Typ 2 is an IgG4-independent pancreatic disease. For both entities pancreas cancer is the most important differential diagnosis. CASE REPORT: We report the case of an 82-year-old male patient who primarily presented with obstructive jaundice. Computed tomography (CT) revealed the typical image of a small cancer of the head of the pancreas with pulmonary metastases. After endoscopic drainage of the bile duct a CT-guided biopsy of a pulmonary nodule was performed in which cancer was ruled out. Next the patient was treated with steroids because of "tumour-associated cachexia". In the follow-up the mass in the head of the pancreas like the lung nodules had surprisingly disappeared. In the complete work-up the immune histochemical staining of the lung biopsy revealed subsequently a typical IgG4-associated inflammation. After termination of the therapy the disease relapsed as sclerosing cholangitis. CONCLUSION: The IgG4-related systemic disease with AIP can present as cancer of the pancreas with lung metastases. Extrapancreatic IgG4-positive histopathology and response to therapy with steroids can help to diagnose the disease in complex clinical presentations.

[Intraductal papillary neoplasms of the bile duct (IPNB). Diagnostic criteria, carcinogenesis and differential diagnostics]. / Intraduktale papilläre Neoplasien der Gallenwege (IPNB). Diagnosekriterien, Karzinogenese und Differenzialdiagnosen.

Intraductal papillary neoplasms of the bile duct (IPNB) are rare precursor lesions of intrahepatic and extrahepatic cholangiocarcinoma that follow an adenoma-carcinoma sequence. According to the histomorphology and the distinct immunohistochemical mucin pattern, four different subtypes are recognized: pancreatobiliary, intestinal, gastric and oncocytic. Differential diagnoses include micropapillary lesions (biliary intraepithelial neoplasms), papillary cystic lesions (intraductal tubulopapillary neoplasms) and cystic lesions (mucinous cystic neoplasms).

Inflammation and mitochondrial fatty acid beta-oxidation link obesity to early tumor promotion.

Obesity is associated with increased risk for developing pancreatic cancer, and it is suggested that insulin resistance provides the missing link. Here we demonstrate that under the context of genetic susceptibility, a high fat diet (HFD) predisposes mice with oncogenic K-ras activation to accelerated pancreatic intraepithelial neoplasm (PanIN) development. Tumor promotion is closely associated with increased inflammation and abrogation of TNFR1 signaling significantly blocks this process underlining a central role for TNFalpha in obesity-mediated enhancement of PanIN lesions. Interestingly, however, despite increased TNFalpha levels, mice remain insulin sensitive. We show that, while aggravating tumor promotion, a HFD exerts dramatic changes in energy metabolism through enhancement of pancreatic exocrine insufficiency, metabolic rates, and expression of genes involved in mitochondrial fatty acid (FA) beta-oxidation that collectively contribute to improved glucose tolerance in these mice. While on one hand these findings provide significant evidence that obesity is linked to tumor promotion in the pancreas, on the other it suggests alterations in inflammatory responses and bioenergetic pathways as the potential underlying cause.

[New insights into the origin of pancreatic cancer. Role of atypical flat lesions in pancreatic carcinogenesis]. / Neue Einblicke in die Entstehung des Pankreaskarzinoms. Die Rolle der atypischen flachen Läsionen in der Karzinogenese.

The identification and characterization of precursor lesions is fundamental to develop screening programs for early diagnosis and treatment, aiming at reducing cancer-related mortality. Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease that becomes clinical apparent only in advanced stages. In order to enable screening procedures for early detection of PDAC, an exact characterization of precursor lesions is of utmost importance. Pancreatic intraepithelial neoplasias (PanIN) are the most frequent and best characterized precursors of PDAC and are lesions with a ductal phenotype thus indicating a ductal cell origin of PDAC. However, evidence from genetically engineered mouse models suggests that tubular complexes (TC) originating through a process of acinar-ductal metaplasia (ADM) form atypical flat lesions (AFL) that may represent an alternative pathway of pancreatic carcinogenesis. Based on a thorough morphological and genetic analysis of murine TC, AFL and PanIN and their human counterparts, a new dual model of pancreatic carcinogenesis is proposed taking into account the role of AFL as possible new precursors of PDAC.

Malignant pancreatic tumors in children and young adults: evaluation of 228 patients identified through the Surveillance, Epidemiology, and End Result (SEER) database.

BACKGROUND: Malignant pancreatic tumors are rare in young patients, few epidemiologic data are available. We reviewed prognostic factors and outcome of 228 patients <30 years with malignant pancreatic tumors identified through the U.S. National Cancer Institute's SEER (Surveillance, Epidemiology, and End Results) Public-use Database from 1973 to 2004. METHODS: Cases were grouped using the ICD-O-3. 5-year overall survival (OAS) was assessed by gender, ethnicity, SEER stage, and 5-year age intervals using univariate and Cox regression analysis. RESULTS: 228 patients with malignant pancreatic tumors were identified, resulting in an incidence of 0.46/million (100 carcinomas, 85 endocrine tumors, 8 solid pseudopapillary neoplasms (SPN), 11 pancreatoblastomas) in the USA. OAS was worse in males than females (37% vs. 55%, p=0.005). OAS according to stage was 87%, 68%, 21% for local (n=54), regional (n=42), distant metastatic disease (n=108), respectively. OAS of patients with carcinoma was 33%, endocrine tumors 58%, SPNs 88%, pancreatoblastomas 66%. Cox regression revealed stage (p=< 0.001), histology (p=< 0.001), age group (p=0.05) to be independent prognostic factors. CONCLUSION: Malignant pancreatic tumors are extremely rare in children and young adults. Entities change over the age groups towards more carcinomas with worse outcome in older patients. Tumor stage, histology and age group are important predictors for outcome. International collaboration is needed to learn more about pediatric pancreatic tumors.

[Neuroendocrine neoplasms of the appendix and colorectum]. / Neuroendokrine Neoplasien der Appendix und des Kolorektums.

Appropriate diagnosis and treatment of neuroendocrine neoplasms (NENs) of the appendix and colorectum requires a detailed knowledge of their proper classification according to the updated WHO and TNM systems. The WHO classification distinguishes well differentiated NEN, the neuroendocrine tumors (G1 and G2 NETs), from the poorly differentiated carcinomas (G3 NECs). While NETs are common in the appendix and rectum, NECs occur predominantly in the colon. G1 appendiceal and rectal NETs of 1 cm in size or below that do not invade either the muscular wall or vessels bear almost no metastatic risk and can be treated by appendectomy or endoscopic resection. G2 appendiceal and rectal NETs larger than 1 cm in size in combination with other risk factors have an increased risk of metastasis and need to be treated more aggressively. NECs of the colon usually require chemotherapy in addition to resection. Today, most patients with NETs of the appendix and rectum have an excellent prognosis when these diagnostic and therapeutic guidelines are borne in mind.

[Sporadic pancreatic head sarcoidosis: a rare clinical case analysis].

Systemic sarcoidosis is an autoimmune disease with a prevalence of 40 per 100,000 people and which mostly affects young adults. It is characterized by non-caseous granulomatous changes of interstitial tissue, predominantly in the lungs. Extrapulmonal sarcoidosis has been described in every organ, but is present only in 1-5% with pancreatic involvement. Furthermore, sarcoidosis leading to a symptomatic mass in the pancreas is extremely rare and must then be differentiated in particular from cancer and pancreatitis. For therapy, it is crucial to find the right diagnosis before planning an operation--otherwise overtreatment by surgery may be an unwanted consecution.

Neuroendocrine tumors of the stomach (gastric carcinoids) are on the rise: small tumors, small problems?

Well differentiated neuroendocrine tumors (NETs) of the stomach (gastric carcinoid tumors) are observed more often, with a tenfold increase in the US in the last 30 - 35 years, and the prognosis has improved greatly in that time. Nowadays most carcinoids of the stomach are diagnosed at an early stage. Four types of gastric NETs have been proposed and recognition of the type is important for defining the diagnostic approach and treatment. Often gastric NETs (especially type 1) are found incidentally during a gastroscopy performed for other reasons; most of these NETs are smaller than 20 mm in size. Conservative management and endoscopic surveillance is adequate for well differentiated, multifocal gastric carcinoids (type 1 or type 2 gastric NETs) that are less than 10 - 20 mm in diameter, unless they show angioinvasion, infiltrate the muscular wall, or have a proliferation rate above 2 %. Endoscopic ultrasound is the method of choice to determine tumor size and depth of infiltration. It is essential to distinguish between multifocal (types 1 and 2) and unifocal type 3 or type 4 gastric NETs, since surgery is indicated for type 3 gastric NETs larger than 10 mm in diameter and for poorly differentiated (localized) neuroendocrine gastric carcinomas (type 4 gastric NET). For optimal management, the type, biology, and stage of the tumor as well as the individual situation of the patient must be considered. Most patients with well differentiated gastric NETs can be treated conservatively and be followed up with endoscopic surveillance.

[Neuroendocrine tumors of the small bowels are on the rise: early tumors and their management]. / Neuroendokrine Tumoren des Dünndarms nehmen zu: frühe Tumoren und deren Management.

Neuroendocrine tumors (NETs) of the small bowels are on the rise: in the US they have increased by 300-500% in the last 35 years. At the same time their prognosis has been much improved. Most NETs of the duodenum are nowadays detected "incidentally" and therefore recognized at an early stage. Duodenal NETs that are well differentiated, not larger than 10 mm in greatest dimension and limited to the mucosa/submucosa can be endoscopically resected. In NETs with a size between 10 mm and 20 mm the therapeutic strategy has to be individually discussed. Endoscopic ultrasound is the method of choice to determine tumor size and depth of infiltration. Surgery is indicated for well differentiated duodenal NETs greater than 20 mm, for localized sporadic gastrinomas and for localized poorly differentiated NE cancers. Surgery is also indicated for localized/regional ileal NETs. Advanced ileal NETs with a carcinoid syndrome are treated with stable somatostatin analogs. This treatment also significantly improves the (progression-free) survival in patients with metastatic NETs of the ileum. For optimal NET management tumor biology, type, localization and stage of the neoplasm as well as the individual situation of the patient have to be taken into account.

[Neuroendocrine tumors of the stomach. Risk stratification and therapy]. / Neuroendokrine Tumoren des Magens. Risikostratifizierung und Therapie.

The diagnosis and therapy of neuroendocrine tumors (NETs) of the stomach are based on their exact classification and risk stratification. Since the incidence of gastric NETs has risen sharply over the last 35 years and most tumors are detected endoscopically at an early stage, they have come to represent a challenge for the pathologist. Gastric NETs are classified according to the WHO and TNM classifications and additionally separated into four biologically distinct types: Well differentiated type 1 and 2 gastric NETs (G1) smaller than 2 cm, and type 3 smaller than 1 cm that do not infiltrate the muscularis propria or show angioinvasion have a good prognosis and can be removed endoscopically. Well differentiated type 1 and 2 gastric NETs (G1-G2) larger than 2 cm or type 3 with a diameter above 1 cm or with infiltration of the muscular wall and/or angioinvasion and poorly differentiated (type 4) neuroendocrine carcinomas carry a poor prognosis and need to be treated aggressively. Endosonography is the method of choice for determining the size, depth of infiltration and presence of lymph node metastases. With exact diagnosis and adequate treatment, the majority of patients with gastric NETs have a favorable prognosis.