An unusual mature thyroid teratoma on CT and 99Tcm scintigraphy imaging in a child.

We report the imaging findings of a mature thyroid teratoma in a 5-year-old girl. Nuclear imaging showed a decrease in (99)Tcm uptake in the right lobe of the thyroid gland. CT scan showed a slightly lobulated soft-tissue mass without calcification, fat or cystic components. Histological analysis showed that the tumor was composed of mature neural tissue, cartilaginous, and epithelial elements. This case study provides new insights into the CT appearance of mature thyroid teratomas.