PitNET in Multiple Endocrine Neoplasm

Sang Ouk ChinCanada Speaker PitNET in Multiple Endocrine NeoplasmMultiple endocrine neoplasia type 1 (MEN1) is a hereditary autosomal-dominant syndrome involving neoplasms of the parathyroid glands, pituitary gland, and endocrine components of the gastrointestinal system. Pituitary neuroendocrine tumors (PitNETs) develop in roughly 40% of individuals with MEN1 and constitute the initial clinical presentation in approximately 10% of cases. Recent epidemiological data indicate a modest female predominance, with tumors smaller than 1 cm occurring more frequently than larger lesions. Hormone-secreting PitNETs are observed more often than non-functioning tumors, representing nearly 36–48% of cases, and prolactin-secreting adenomas remain the most prevalent subtype. In comparison with sporadic PitNETs, those associated with MEN1 are more likely to exhibit plurihormonal secretion, greater tumor size, and locally aggressive behavior, while age at diagnosis and the relative frequency of functional tumors appear comparable. Patients lacking detectable MEN1 gene mutations often present with larger and more clinically apparent PitNETs at diagnosis. Although rare, pituitary carcinoma has been documented in six patients with MEN1, including one individual without an identifiable MEN1 mutation. Current evidence suggests that management strategies for MEN1-related PitNETs largely parallel those used for sporadic tumors. PitNETs have also been described in multiple endocrine neoplasia type 4 (MEN4), though comprehensive epidemiologic characterization remains limited, and MEN4 should be considered in patients with MEN1-like clinical features and negative MEN1 genetic testing.