Uptake of Technetium 99-Pertechnetate in a Primary Thyroid Carcinoma: Need for Caution in Evaluating Nodules

The case of a 49-yr-old man is presented in which, on the scintiphoto, a primary thyroid carcinoma is seen to take up 99mTc-pertechnetate relatively better than the normal surrounding gland. This finding suggests significant trapping in the lesion. The 125I-iodine radioautograph, however, indicated decreased retention of iodine in the tumor. In man the association of intact trapping with poor retention of iodine in a primary thyroid carcinoma is unusual. The 99mTc-pertechnetate image in this case, when interpreted alone, can be misleading.