Primary squamous cell carcinoma of the thyroid.

摘要

A 66-year-old man presented with a pathological fracture of the right humerus because of metastatic squamous cell carcinoma (SCC), histologically proven by open biopsy. Axial contrast enhanced computed tomography (CT) of the neck (Fig. 1a) showed two enlarged left cervical lymph nodes and a focal hypodense nodule in the left thyroid lobe, showing increased glucose metabolism on F-18-fluorodeoxyglucosepositron emission tomography (fused with transaxial CT in Fig. 1b). Other lesions were notdetected. As a complete otorhinolaryngological examination and panendoscopy did not show any primary malignancy, tonsillectomy, left neck dissection comprising levels II-IV and left hernithyroidectomy were carried out. Histology of the palatine tonsils did not show malignancy, whereas two resected lymph nodes showed metastatic infiltration with poorly differentiated SCC. Histological and imrnunohistochemical investigation of the thyroid tumour was consistent with SCC with focalformation of intercellular bridges, showing intensive cytoplasmaticexpression of cytokeratin CK5/6 (Fig. 2) and moderate coexpression of CK7, CK18 and CK19. The Ki67 proliferation index (done MiB1) was 20%. The neoplastic cells were negative for thyroglobulin and thyroid transcription factor.