Advances in the diagnosis and treatment of mixed thyroid malignancies

WU Yi-jun; PAN Jun; LI Cui-wei; GAO Xing-xing

doi:10.19538/j.cjps.issn1005-2208.2025.09.18

Abstract：Mixed thyroid malignancies are rare tumors characterized by the coexistence of two or more distinct histological types within the same thyroid gland.Common forms include papillary thyroid carcinoma(PTC)combined with medullary thyroid carcinoma(MTC),PTC combined with follicular thyroid carcinoma(FTC),MTC combined with FTC,and differentiated thyroid carcinoma(DTC)combined with anaplastic thyroid carcinoma(ATC).The components may display tightly interwoven,partially separated,or spatially independent patterns,leading to the formation of mixed tumors,composite tumors,or collision tumors.The underlying pathogenesis remains unclear,with major hypotheses including the incidental theory,microenvironmental alteration theory,and stem cell theory.Diagnosis relies on imaging studies,fine-needle aspiration or core needle biopsy combined with immunohistochemistry and genetic testing(e.g.,BRAF,RET mutations),with postoperative pathology serving as the diagnostic gold standard.Treatment strategies should be guided by the most aggressive component.Surgery is the primary modality and is often combined with radioactive iodine therapy,thyroid hormone suppression,targeted therapy,or immunotherapy.Tumors containing an MTC component require dynamic monitoring of serum calcitonin(Ctn)and carcinoembryonic antigen(CEA),whereas those with an ATC component often necessitate multimodal chemoradiotherapy and targeted therapy.Prognosis depends on the most malignant component:PTC-FTC subtypes generally have favorable outcomes,while those involving ATC or sarcomatous components are associated with extremely poor survival.Overall,mixed thyroid malignancies exhibit marked clinical heterogeneity,necessitating individualized management and long-term follow-up.