Abstract:

Objective To explore the clinicopathological characteristics and differential diagnosis of sarcomatoid thyroid carcinoma（STC）. Methods One case of oral soft tissue metastasis from STC without thyroid focus was reported and the relevant literatures were reviewed. Results The patient was a 63 years old woman. A polypoid mass with peduncle was located in the right upper jaw. Histopathologically， STC was a widely invasive tumour composed of an admixture of spindle cells， pleomorphic giant cells and epithelioid cells. The nuclei were bizarre and single or multiple. They revealed prominent nucleoli. Mitotic figures could be numerous. Extensive coagulative necrosis with accompanying polymorphonuclear leukocytes was often seen. Immunohistochemically， tumour cells expressed TTF-1， Vimentin， CKpan， SMA and Ki-67. CK7 was only positive in a few tumour cells. Tg， CD68， LCA， Myogenin， MG， HMB45 and S-100 were negative. Conclusion Oral soft tissue metastasis of STC is rare. It is a highly malignant tumour with poor prognosis. The diagnosis of STC should be based on clinical history， histopathological changes and immunohistochemical tests. It should be distinguished from other tumours.