Multiple Endocrine Neoplasia type 1 (MEN1) is a rare autosomal dominant disorder characterized by the combined occurrence of tumors in the parathyroid glands, anterior pituitary, and pancreatic neuroendocrine cells. While primary hyperparathyroidism is the most common manifestation, pancreatic neuroendocrine tumors (pNETs) are the leading cause of disease-related mortality. Data regarding the clinical progression and mutational spectrum of MEN1 in the Vietnamese population remains limited. This study presents the clinical and genetic features of two Vietnamese patients presenting with multiple pancreatic tumors and confirmed MEN1 germline mutations.

We conducted a retrospective analysis of two unrelated patients diagnosed with MEN1 at Choray hospital, HCMC, Vietnam. The diagnosis was established based on clinical criteria (presence of two out of the three main MEN1-associated tumors) and confirmed via Sanger sequencing of the MEN1 gene. Clinical history, biochemical profiles (calcium, PTH, insulin, gastrin, chromogranin A), and imaging results (CT/MRI/EUS) were reviewed.

Case 1: A 28-year-old female presented with Whipple's traid during a year. Computed Tomography (CT) and Endoscopic Ultrasound (EUS) revealed multiple hypervascular nodules in the pancreatic body and tail, ranging from 1 to 2 cm. Genetic analysis identified a heterozygous germline mutation NM_001370259.2:c.722G>A NP_001357188.2:p.Cys241Tyr in the MEN1 gene. The patient underwent Radiofrequency Ablation- Endoscopy Ultrasound (RFA-EUS), with pathology confirming well-differentiated neuroendocrine tumors Grade 1. Case 2: A 37-year-old female was referred for evaluation of persistent hypercalcemia. Abdominal MRI identified diffuse enlargement of the pancreas with five distinct masses consistent with multifocal pNETs. Although the patient was asymptomatic for hormone hypersecretion, biochemical screening revealed elevated Chromogranin A. Genetic testing confirmed a distinct pathogenic variant NM_001370259.2:c.1460_1462del (NP_001357188.2:p.Ser487Ter).

These cases illustrate the phenotypic complexity and high penetrance of pancreatic involvement in Vietnamese MEN1 patients. The presence of multifocal pNETs underscores the necessity for aggressive surveillance using sensitive imaging modalities like EUS. Furthermore, the identification of specific MEN1 mutations in this cohort contributes to the expanding genetic database of MEN1 in Vietnam, facilitating earlier diagnosis and family screening to improve long-term prognosis.