Metastatic grade 3 gastric neuroendocrine tumor expressing somatostatin receptor in Multiple Endocrine Neoplasia Type 1 (MEN1) syndrome

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Introduction: Gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs) can occur in 30-70% of patients with MEN1. However, only 1% of GEP-NENs are Grade 3 (G3). Treatment for advanced GEP-NENs in MEN1 is based on the treatment guidelines for sporadic GEP-NENs.

Aim(s): To present a case of G3 GEP-NEN.

Materials and methods: A 43-year-old male with MEN1 followed at our institution for 23 years with hyperparathyroidism, non-functional pancreatic NEN and Zollinger-Ellison-Syndrome. On surveillances scans, at age 40, a 68Ga-DOTATATE positron emission tomography (PET) scan showed an intraluminal mass on the medial aspect of the gastric wall. Anatomical imaging studies showed two enhancing masses within the pancreas and a rounded mass-like thickening along the lesser curvature of the stomach. The gastric mass was resected, and pathology reported a well-differentiated G3 NEN with a Ki-67 >20%. Patient continued active surveillance and lanreotide. 18 months later cross-sectional imaging studies showed findings consistent with metastatic disease within the right hepatic lobe and bland embolization was recommended. Somatic mutation analysis (TruSight Oncology 500 (TSO500), Illumina) of a liver metastasis biopsy showed loss of heterozygosity at the MEN1 germline variant locus in the tumor tissue. Variants of uncertain significance were found in ATM, E2F3, FAT1, FLCN, MAP3K4, and NRG1.

Conference: 18th Annual ENETS Concerence (2021)

Presenting Author:

Authors: Graf A, Welch J, Mandl A, Parekh V, Cochran C,

Keywords: case report, multiple endocrine neoplasia type 1, gastroenteropancreatic tumor grade 3,