Endocrine Abstracts

Introduction: The MEN1 syndrome is caused by inactivating mutations of MEN1, a tumor suppressor gene encoding menin. A sporadic presentation is relatively rare (8-14%) and could be due to de novo mutations.

Aim: To present an MEN1 case diagnosed following a routine consultation for amenorrhea

Case presentation: A 44-year-old female presented with secondary amenorrhea and a history of complicated renal lithiasis requiring repeated urological intervention. Biochemical workup showed moderate hyperprolactinemia (78 ng/ml) and pituitary MRI demonstrated a microprolactinoma, as well as primary hyperparathyroidism with mild hypercalcemia. Bilateral inferior parathyroid adenomas were identified on neck ultrasound examination and confirmed through PTH measurement in FNAB aspirate. Family history was negative for MEN1 manifestations, but the father had died suddenly at 41 yrs of age. There were no clinical manifestations suggestive of neuroendocrine pancreatic tumours.

Management: Prolactinemia was normalized with cabergoline treatment (1 mg/week) and the menses resumed. The patient underwent parathyroid surgical exploration; a right inferior parathyroid adenoma was removed and the left adenoma was not identified, leading to a central compartment dissection and block removal of central lymph nodes; superior parathyroids were macroscopically normal and were preserved. Postoperatively, calcium and PTH were normalized. Postoperatively, results of MEN1 Sanger sequencing of coding exons 2-10 and adjacent intronic sequences identified a likely pathogenic small insertion heterozygous mutation NM_001370259.2:c1700_1701insTTGGTGGC, leading to a frameshift (p.Thr568Trpfs*23). Further workup for MEN1-associated neuroendocrine tumors, as well as genetic screening of family members is pending.

Conclusions: Our patient illustrates an atypical presentation of MEN1, as well as management challenges of hyperparathyroidism in this setting. Genetic testing is recommended in sporadic cases and cases with high suspicion (e.g. multigland hyperparathyroidism). A de novo MEN1 mutation remains a possibility in our patient, but its demonstration will be difficult, due to a deceased parent.