OCCULT THYROID-CARCINOMA MANIFESTED AS A LARGE MEDIASTINAL TUMOR

The authors report a rare case of clinically occult thyroid carcinoma that initially manifested as a metastatic mediastinal tumor with trach eal stenosis, A curative operation was performed by complete removal o f the tumor through a median sternotomy approach combined with resecti on of the tracheal invasion. Histopathological examination revealed tr ansition of a well-differentiated papillary carcinoma into a poorly di fferentiated component in the lesion invading the trachea, which sugge sted that this transition might have rendered the tumor more aggressiv e, leading to tracheal invasion.