Endocrine Abstracts

Pancreatic incidentalomas are defined as asymptomatic pancreatic lesions, discovered incidentally by imaging for an unrelated indication. A significant proportion of these tumors may be malignant or have a malignant potential. As the use of improved cross sectional imaging increases incidentalomas are becoming more common. In the ENETS guidelines it is proposed that selected patients with incidentally found sporadic, asymptomatic, non-functioning (NF) pancreatic neuroendocrine neoplasms (pNEN) less than 2 cm in size may be followed with repeated imaging instead of resected. However, this conclusion is based on limited data as only few and retrospective studies with a heterogeneous design have investigated the safety of active surveillance. Only few patients had histological or cytological diagnosis and the Ki67 proliferation index, which is the most powerful prognostic marker in NF pNEN, was only determined in 10% of the patients. Up to 20% (in a single study 50%) of the patients had significant tumor growth although regional lymph node metastases developed in few patients. In a recent study, 38% of pNEN <2 cm displayed malignant features. Hence, it cannot be predicted which patients will progress during observation. Accordingly, active surveillance is a doubtful approach and resection should be offered patients with small NF pNEN, if not contraindicated by age, severe co-morbidity and poor performance status. Surgical procedures for small NF pNEN are safe when performed in high-volume centers. In contrast, in MEN-1 patients NF pNEN ≤ 2 cm are generally indolent tumors with low malignant features and surgical treatment is rarely indicated.