Therefore, we provide further evidence that parathyroid tumors in MEN1 are multiple monoclonal tumors and not hyperplastic changes, supporting the nomenclature of multi-glandular adenomas as suggested in the novel WHO classification of “Endocrine and Neuroendocrine Tumours” (5th edition, 2022) [38]. The gene discussed is MEN1; the disease is tumor of parathyroid gland.