Background: Multiple Endocrine Neoplasia Type 1 (MEN1) is a rare autosomal dominant syndrome that predisposes individuals to multiple endocrine tumours, predominantly affecting the parathyroid, anterior pituitary and pancreatic islet cells. This unusual case shows features of three of the main MEN1 tumour types, yet genetic testing was negative for the MEN1 mutation.
Case esentation: A 56-year-old lady first presented with hypercalcaemia. She was fit and well and took no regular medications. There was no significant family history. She was investigated for a cause of her primary hyperparathyroidism [Ca2+ = 2.9 mmol/L (<2.65); PTH = 11.9 μmol/L (1.39.3)], which identified a left inferior parathyroid adenoma. Between follow-up appointments, a transient ischaemic attack was suspected. The CT-head found a pituitary mass. Subsequent MRI-head identified a 16×12×10 mm pituitary mass without compression of the optic chiasm. Pituitary function tests were within normal limits, confirming a non-functioning adenoma. MEN1 was suspected warranting further investigation. Fasting gut peptides revealed elevated gastrin levels [375 pmol/L (040)]. With features of the three primary MEN1 tumour sites now present, she was referred for genetic testing and MR-pancreas and Octreotide imaging to investigate for gastrinomas. During this time, she underwent left inferior parathyroidectomy. MR-Pancreas and Octreotide imaging failed to identify gastrinomas. Genetic testing did not reveal partial or whole MEN1 gene deletion.
Conclusion: This unusual case demonstrates significant diagnostic and management challenges. Despite phenotypically exhibiting MEN1 features, there is no genotypic correlation. Current management consists of regular surveillance for tumour progression.