In summary, these observations suggest that FLCN mutations, particularly biallelic mutations, whether occurring in BHD patients or sporadically, may contribute significantly to the pathogenesis of thyroid neoplasms that may have a propensity toward oncocytic features, underscoring the need for further study into the molecular mechanisms and clinical implications of FLCN alterations in thyroid cancer. This evidence concerns the gene FLCN and thyroid tumor.