Sarcoma of the thyroid co-occurrence with Carcinoma (Carcinosarcoma)

Thyroid carcinosarcoma (TC) is an aggressive biphasic malignancy. It has a high mortality rate even after the application of a Multi-disciplinary therapeutic approach. We studied a 63-year-old lady with neck swelling for 4 years with a rapid increase in size in 2 months. Fine Needle Aspiration Cytology (FNAC) of the thyroid nodule was reported as papillary thyroid carcinoma. Positron Emission Tomography and Computed Tomography (PETCT) showed a hypermetabolic lesion in the thyroid with a hypermetabolic lytic lesion in the 4 th rib, suggestive of metastasis. Subsequently, patients underwent total thyroidectomy with central compartment clearance and left selective neck dissection. Histopathological evaluation and immunohistochemistry showed that spindle cells were positive for smooth muscle actin (SMA) and negative for Pan Cytokeratin (Pan CK), Carcinoembryonic Antigen (CEA), Paired-box-gene (PAX8), SRY-related HMG-box 10 (SOX10) and Desmin. Thyroid transcription factor 1 (TTF-1) was positive in follicular cells and Cytokeratin 19 (CK19) was focal positive. Hence, a diagnosis of Sarcoma with myoid differentiation and Follicular Carcinoma (carcinosarcoma) was made. Treatment of this disease remains not very clear. The method of management in is still Surgical removal of primary tumor.