Unveiling a rare endocrine puzzle: A case of CDKN1B mutation-associated MEN4 syndrome

A woman with a prior diagnosis of thyroid dysfunction was found to have hyperprolactinemia and incidental hypercalcemia. Further investigation led to the diagnosis of a parathyroid adenoma. The unique constellation of hormonal abnormalities and multifocal thyroid nodules defied explanation by known MEN syndromes (no family history). We report the identification of a heterozygous p.Val109Gly mutation in CDKN1B, a gene associated with MEN4 syndrome, through targeted genetic testing. The presented case expands the phenotypic spectrum of MEN4 and highlights the utility of genetic testing in diagnosing syndromic forms of endocrine hyperplasias. •Complex Endocrine Disorder: A patient presented with thyroid dysfunction, hyperprolactinemia, and hyperparathyroidism.•MEN4 Diagnosis: Genetic testing identified a p.Val109Gly mutation in the CDKN1B gene, in MEN4.•Clinical Implications: MEN4 diagnosis increases neuroendocrine tumor risk, requiring regular screening and surveillance.•Genetic Testing Value: This case underscores genetic testing’s role in diagnosing complex endocrine disorders.