[Non-functional duodenal neuroendocrine neoplasia in the proximal duodenum--case reports and proposal for a "high-risk-/low-risk-concept" in the decision for local endoscopic therapy]. / Nicht-funktionelle duodenale neuroendokrine Neoplasien im proximalen Duodenum--Fallserie und Vorschlag für ein "High-Risk-/Low-Risk-Konzept" zur Entscheidung für eine lokale endoskopische Therapie.

Early duodenal neuroendocrine neoplasms (dNENs) are being increasingly diagnosed. Non-functional dNENs in the bulb expressing gastrin are by far the most frequent entity. In the period from 2004 to 2012, 17 cases of 16 patients with NET in the duodenal bulb were evaluated. dNENs of the ampulla of Vater and functional dNEN/gastrinoma were not included due to possibly different malignant potentials. The average age of the patients was 65.7 years, the mean tumour size was 10.2  mm, the maximum proliferation index Ki 67 was 5 % (NET G2). In most cases the maximum depth of invasion was down to the submucosa. In cases of dNEN without risk factors (size up to 10 mm, G1 situation, no invasion of the muscularis propria, no angioinvasion) in 10 out of 11 cases (90.9 %), endoscopic therapy was sufficient. In cases of existing risk factors, sole endoscopic treatment was only possible in 1 out of 5 cases (20 %). In the absence of risk factors in the current follow-up period (mean: 36.7 months) no lymph node metastases were detected. In the presence of risk factors or indications for surgery we found an increase in the rate of lymph node metastases. Our own data indicate that in case of a G2 situation, a tumour size >10  mm or infiltration of the muscularis propria the need for surgical treatment increases significantly for early non-functional dNENs in the duodenal bulb. A high-risk-/low-risk-concept for the endoscopic therapy for early non-functional dNEN has been established.

[Endoscopic therapy for gastroduodenal neuroendocrine neoplasms]. / Endoskopische Therapie gastroduodenaler neuroendokriner Neoplasien.

Neuroendocrine neoplasms (NEN) represent a group of potentially malignant tumors, which can be located in every section of the gastrointestinal tract, the pancreas and the bronchopulmonary system. Gastroduodenal NENs have a relatively good prognosis in comparison to other subentities, e.g. pancreatic or ileojejunal NENs. In the stomach there are four different types of NENs, while in the duodenum there are five types and all vary in the malignant potential and the therapeutic approach. Due to the simple access endoscopic methods not only have diagnostic but also important therapeutic relevance in this subgroup. Lesions smaller than 1 cm can easily be resected with forceps or snare resection and for larger lesions up to 2 cm more invasive strategies, such as endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) are available. Important criteria in gastric NEN for the risk evaluation of endoscopic treatment alone are the size of the lesion, depth of invasion and the tumor biology, e.g. neuroendocrine tumor (NET) G1/G2 versus neuroendocrine carcinoma (NEC) G3. In duodenal NEN the aforementioned risk factors also apply and in addition only lesions outside the ampulla of Vater should be endoscopically resected whereas periampullary lesions need to be addressed surgically. As an individualized therapeutic approach the possibility of a combined endoscopic and laparoscopic resection technique exists. Follow-up endoscopic investigations are necessary, especially in gastric type 1 NENs, which have a tendency to relapse.