Fig. 4

A 45-year-old male patient presented with anterior mediastinal metastatic PTC lesions and occult primary on imaging. Histopathology examination of the resected thyroid gland revealed micro-foci of PTC; the largest, in the isthmus, measured 4 mm. a Transverse greyscale ultrasound of the thyroid demonstrates homogenous gland with normal echogenicity and size. No focal lesion or micro-calcifications. b Non-enhanced CT scan obtained as part of PET/CT examination shows a heterogeneous, large, relatively dense anterior mediastinal mass (white arrow) with peripheral calcification (arrowheads). Thyroid gland has normal CT appearance with no abnormal FDG uptake (not shown)