Pancreatic NENS - Diagnosis and Management
Rungsun Rerknimitr, MD, FRCP (London), FASGE
Chulalongkorn University, Bangkok, Thailand

Although in 2018 WHO has classified neuroendocrine tumor in three grades according to their classification, ICD-11 does not support the idea to completely divide them to benign or malignant tumor. The reasons are related to research funding and the difficulty to access novel therapies. Therefore, neuroendocrine neoplasm (NEN) is the more preferred terminology. The digestive organs represent 60% of affected organs and pancreas involves about 10% of the overall cases. Interestingly, those functional pancreatic-NENs constitute about 30–40% of all pNENs displaying many different clinical syndromes including insulinoma, glucagonoma, VIPoma, etc. Insulinoma patient presents as refractory hypoglycemia, gluconoma patient may show as necrolytic erythrema skin lesions, whereas VIPoma patient suffers from watery diarrhea with hypokalemia. Among those pancreatic-NENs, insulinomas are the most common functional neoplasms (21%) and majority of them are benign. Traditionally, surgery is the main stay of treatment for those small NENs. One of the advantages of surgery is its curative result in those malignant NENs with potential aggressive behavior. However, insulinoma may require only local ablation, therefore there have been growing evidence on radiofrequency ablation (RFA) approached by endoscopic ultrasonography (EUS). The typical, findings from EUS in low grade pancreatic-NENs (G1 and G2) are well round hypoechoic lesions with clear margins), whereas the EUS findings in high grade pancreatic-NENS (G3 and carcinoma) are unclear and irregular margins with internal central necrosis. In addition, pancreatic duct compression and/or invasion are the characters in advanced lesions. The current recommendation for tissue acquisition is fine needle biopsy instead of aspiration because grading and differentiation are more difficult with aspirated specimens. Lastly, there are growing series of EUS-RFA for the treatment of insulinomas in term of technical successful and efficacy. EUS approach is more repeatable than surgery especially when apply in Multiple-Endocrine-Neoplasia patient with high risk of new development of Pancreatic-NENs.