MEN1 and secondary hyperparathyroidism: The current WHO 2022 classification of parathyroid tumors aims to pathologically distinguish parathyroid disease secondary to germline mutations, i.e., multiglandular multiple parathyroid adenomas as seen with syndromic forms of PHPT (e.g., MEN1 due to MEN1 mutations) or parathyroid carcinoma due to CDC73 mutations, from that of parathyroid hyperplasia, usually seen in patients with secondary hyperparathyroidism (e.g., chronic renal failure) [25].