Molecular, Biochemical, and Bioimaging Markers of MEN Syndromes.

Multiple endocrine neoplasia (MEN) syndromes are rare hereditary disorders characterized by the development of multiple endocrine and non-endocrine tumours with variable penetrance and age-dependent expression. Although uncommon, these syndromes are highly relevant from both biological and clinical perspectives, as they exemplify the direct link between germline genetic alterations and tumorigenesis. Early tumour detection is critical in MEN syndromes because many associated neoplasms-such as medullary thyroid carcinoma (MTC), pancreatic neuroendocrine tumours (NETs), pheochromocytomas, and parathyroid disease-may remain clinically silent for prolonged periods while retaining malignant potential. Delayed diagnosis is associated with advanced disease and worse outcomes, whereas early identification enables curative or organ-preserving interventions. This clinical challenge has driven the development of integrated diagnostic strategies combining genetic testing, biochemical markers, and imaging. Among these, genetic testing plays a pivotal role, providing definitive diagnosis, enabling family screening, and guiding risk-adapted surveillance. The aim of this review is to provide a comprehensive synthesis of genetically driven diagnostics in MEN syndromes, outlining the current state of the art and future directions in precision medicine.