Poster Presentation ESA-SRB 2023 in conjunction with ENSA

Case A 34-year-old female, recently migrated from Eritrea, presented with gastric outlet obstruction. A 1.7x1.3x1.8cm duodenal mass was identified on CT and endoscopic-biopsy revealed a gastroenteropancreatic-neuroendocrine-tumour (GEP-NET). Gastrin was elevated (17,650pmol/L) and lanreotide was commenced (Table 1). GATATE-PET confirmed a duodenal mass with nodal involvement. A Whipple’s procedure was performed. Histopathology demonstrated multifocal grade-2 pT3N1M1 duodenal gastrinoma (15/35 positive nodes, Ki67 3.5%) alongside gastrin-negative intrapancreatic lesions. Post-operatively, gastrin normalised despite lanreotide cessation. MEN1 was suspected as she had a 12-year history of macroprolactinoma. Despite longstanding cabergoline 0.5mg/week, her first MRI-pituitary in Australia showed a 20x29x25mm Pituitary-NET with optic chiasm distortion, with prolactin 10,260mIU/L. Uptitration of cabergoline was complicated by CSF leak and she underwent transsphenoidal resection and repair. Hyperprolactinaemia persisted post-operatively (latest 1,053mIU/L) and cabergoline was up-titrated to 2.5mg/week. PTH-dependent hypercalcaemia was identified (corrected-Ca 2.87mmol/L, PTH 33.3pmol/L) and although a left superior parathyroid adenoma was suspected on imaging she underwent subtotal-parathyroidectomy after a pathological mutation of MEN1 (c.186dupC) was confirmed, with postoperative hypoparathyroidism. She was referred to genetic counselling and wishes to conceive soon using IVF.

Discussion This case highlights the classic MEN1 triad: hyperparathyroidism, Pituitary-NET and GEP-NET. Multifocal gastrinoma is the most common GEP-NET in MEN1 and GATATE-PET provides highly sensitive functional imaging for GEP-NETs.¹ While generally not curative, surgical debulking is recommended for symptom control.^2,3 Localisation studies may be misleading and subtotal parathyroidectomy plus thymectomy is preferred for hyperparathyroidism due to multi-gland involvement and risk of thymic carcinoid.⁴ Pituitary-NETs occur in 20-40% with MEN1.^5,6 The majority are macroadenomas (mostly prolactinomas) and treatment resistance is more common than sporadic disease.⁶ Dopamine agonists can lead to CSF leak due to macroprolactinoma shrinkage and persistent hyperprolactinemia is common after transsphenoidal resection. Genetic counselling should be offered to affected individuals and first-degree relatives to aid reproductive decisions, tumour surveillance and treatment.