FLCN and Birt-Hogg-Dube syndrome: 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.