Multiple Endocrine Neoplasia Type 1 in Clinical Practice

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disorder characterized by the development of endocrine and nonendocrine tumors. The genetic anomaly underlying the tumorigenesis in MEN1 is loss-of-function mutations of the MEN1 gene. Endocrine tumors in MEN1 patients can be clinically apparent at very young ages, which is why a thorough and regular follow-up of all potentially affected individuals is required. We report the case of an 18-year-old man who was clinically diagnosed with MEN1 based on the presence of primary hyperparathyroidism, incidentally discovered during a hospitalization for acute appendicitis. The subsequent detailed workup revealed that the patient already also had pituitary and pancreatic lesions. The patient belongs to a MEN1 family in which several members refused genetic testing. He was hence unaware of his familial genetic background and had never been subjected to any screening tests. This case exhibits the classic triad of MEN1 manifestations (primary hyperparathyroidism, pancreatic neuroendocrine tumors, and pituitary adenoma) and illustrates the importance of early genetic and clinical diagnosis.