[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.

[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.

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.

Potential role of Th17 cells in the pathogenesis of type 2 autoimmune pancreatitis.

Th17 cells have been shown to play an important role in the pathogenesis of a variety of autoimmune diseases. The aim of this study was to investigate the potential role of Th17 cells in autoimmune pancreatitis (AIP). Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine gene expression of the signature cytokines of Th17 cells IL-17A and IL-21 and of the Th17 lineage-specific transcription factor retinoic acid receptor-related orphan receptor C (RORC) in human tissue specimens of AIP, classical chronic pancreatitis (CP), and normal pancreas (NP). Infiltrating immune cells were characterized by immunohistochemistry (IHC). Gene expression of IL-17A, IL-21, and RORC were found to be significantly increased in AIP. Accordingly, the number of Th17 cells was significantly increased in AIP compared to NP or CP. Both gene expression analysis and IHC revealed a clear difference between type 1 and 2 AIP. In the periductal compartment of type 2 AIP, which is characterized by granulocytic epithelial lesions (GELs), the number of infiltrating Th17 cells and neutrophilic granulocytes was significantly increased compared to type 1 AIP. Our data suggest that Th17 cells play a role in the pathogenesis of AIP, in particular of type 2 AIP. Cross-talk between Th17 cells and neutrophilic granulocytes mediated via IL-17A may be a potential mechanism by which neutrophils are recruited to the duct and acinar cells with subsequent destruction, a process that is pathognomonic for type 2 AIP.

[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.

The search for the primary tumor in metastasized gastroenteropancreatic neuroendocrine neoplasm.

Gastroenteropancreatic neuroendocrine tumors (NETs) often present as liver metastasis from a carcinoma of unknown primary. We recently showed that primary NETs from the pancreas, small intestine and stomach as well as their respective liver metastases differ from each other by the expression profile of the three genes CD302, PPWD1 and ABHB14B. The gene and protein expression of CD302, PPWD1, and ABHB14B was studied in abdominal NET metastases to identify the site of the respective primary tumors. Cryopreserved tissue from NET metastases collected in different institutions (group A: 29, group B: 50, group C: 132 specimens) were examined by comparative genomic hybridization (Agilent 105 K), gene expression analysis (Agilent 44 K) (groups A and B) and immunohistochemistry (group C). The data were blindly evaluated, i.e. without knowing the site of the primary. Gene expression analysis correctly revealed the primary in the ileum in 94 % of the cases of group A and in 58 % of group B. A pancreatic primary was predicted in 83 % (group A) and 20 % (group B), respectively. The combined sensitivity of group A and B was 75 % for ileal NETs and 38 % for pancreatic NETs. Immunohistochemical analysis of group C revealed an overall sensitivity of 80 %. Gene and protein expression analysis of CD302 and PPWD1 in NET metastases correctly identifies the primary in the pancreas or the ileum in 80 % of the cases, provided that the tissue is well preserved. Immunohistochemical profiling revealed CD302 as the best marker for ileal and PPWD1 for pancreatic detection.

[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.

Establishment of robust controls for the normalization of miRNA expression in neuroendocrine tumors of the ileum and pancreas.

There is need to determine tissue-specific robust controls for normalization of microRNA expression to avoid false results and misinterpretation. The aim of this study was to evaluate the expression of different small RNAs in neuroendocrine tumors (NETs) and their suitability as normalizers in miRNA real-time PCR experiments. We investigated the expression of the nine small RNAs miR-93, miR-191, SNORD48, SNORD61, SNORD68, SNORD72, SNORD95, SNORD96a, and RNU6-2 in formalin-fixed, paraffin-embedded tissue samples of 25 ileal NETs by real-time PCR determining the most stable controls for expression normalization using four different algorithms. This analysis was expended to ten pancreatic NETs. Finally, five small RNAs were further tested as normalizers for miRNA-133a expression, which is known to be downregulated in metastases of ileal NETs, in ten matched pairs of ileal NETs and their metastases. Ranking of the expression results revealed the following order of stability from high to low: SNORD61 < SNORD95 < SNORD72 < SNORD96a < SNORD68 < miR-191 < miR-93 < RNU6-2 < SNORD48 for ileal NETs and SNORD95 < miR-93 < SNORD96a < SNORD61 < SNORD68 < SNORD72 < RNU6-2 < miR-191 < SNORD48 for pancreatic NETs. The determination of SNORD61 and SNORD95 for ileal NETs and SNORD95 and miR-93 for pancreatic NETs as good normalizers presents a useful tool for experiments involving the analysis of miRNA expression.

[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).

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.

[Recurrent duodenal ulcer bleeding as the first manifestation of a solid pseudopapillary neoplasm of the pancreas with hepatic metastases]. / Rezidivierte duodenale Ulkusblutung als Erstmanifestation einer hepatisch metastasierten solid-pseudopapillären Neoplasie des Pankreas.

HISTORY AND ADMISSION FINDINGS: In a 17-year-old girl recurrent duodenal ulcer bleeding had led to severe anemia. INVESTIGATIONS: Sonography and computed tomography revealed a partially cystic tumour of the pancreatic head and suspicious hepatic lesions. TREATMENT AND PATHOLOGICAL DIAGNOSIS: A partial duodenopancreatectomy was performed and two liver metastases were resected. Histological examination of the resected pancreatic specimen revealed a solid pseudopapillary neoplasm of the pancreas (SPN) with hepatic metastases. CLINICAL COURSE AND PROGNOSIS: The seven remaining liver metastases were removed in a second procedure (right hepatectomy). One year later two new liver metastases were treated by radiofrequency ablation. Two years after the initial operation, the patient is well and tumor-free. CONCLUSION: SPN is a rare cystic tumor that is mainly found in young women. Direct tumor infiltration of stomach or duodenum can cause gastrointestinal bleedings in rare cases. Resection of the primary tumor and surgical or interventional removal of metastases are the treatment of choice.

[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.

[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.

[Pathology of neuroendocrine neoplasms]. / Pathologie neuroendokriner Neoplasien.

During the last 5 years the European Neuroendocrine Tumor Society (ENETS) has developed basic recommendations for a standardized pathological diagnosis and classification of neuroendocrine neoplasms (NEN) of the gastroenteropancreatic system. These were included in the novel classification of tumors of the digestive system by the World Health Organization (WHO 2010) and the TNM classification of the union for international cancer control (2009). This review presents the pathology diagnosis regarding (1) basic diagnosis, (2) clinically relevant optional diagnosis, (3) proliferation-based grading, (4) nomenclature and (5) TNM classification. It is emphasized that a standardized diagnosis of NEN, together with clinical and radiological findings, is crucial for prognostic stratification and optimal therapy of patients with NEN. Therefore a close interdisciplinary collaboration is essential.