Pancreatic neuroendocrine microtumors in the elderly: A retrospective study using cadaveric pancreatic tissue.

BACKGROUND: Pancreatic neuroendocrine microtumors (PNEMTs) are small (< 5 mm), non-functioning, well-differentiated neuroendocrine neoplasms. Although they are rare, they are not invariably benign. PNEMTs are typically discovered incidentally during autopsy. However, data regarding the occurrence of PNEMTs in the elderly population, particularly those identified incidentally in cadaveric studies, remain limited. AIM: To investigate the prevalence and histopathological characteristics of PNEMTs in elderly individuals by analyzing cadaveric pancreatic tissues. METHODS: We conducted a retrospective analysis of 85 pancreatic specimens (age range: 58-109 years) obtained from cadavers for anatomical education and research at the Department of Life Dentistry, Nippon Dental University. Paraffin sections of the pancreatic head, body, and tail were prepared for histological and immunohistochemical analysis. RESULTS: Five cases with PNEMTs (5/85, 5.9%; male, n = 33; female, n = 52; mean age: 85.8 ± 12.1 years) were identified. The tumors were solitary, well circumscribed, and located within the pancreatic parenchyma (body: n = 4; tail: n = 1), and all were < 5 mm (range: 0.54-2.20 mm) in size. All tumors showed strong chromogranin A and synaptophysin positivity, and were predominantly glucagon (GLU)-positive. Ki-67 immunostaining indicated minimal proliferative activity; therefore, these tumors were considered non-functioning, GLU-producing, well-differentiated grade 1 PNEMTs. CONCLUSION: Small, predominantly low-grade, GLU-secreting PNEMTs were present in 5.9% of elderly individuals, highlighting the prevalence of subclinical PNEMTs and the need for careful follow-up.