Post-therapy radioiodine imaging characterizes occult metastatic differentiated thyroid carcinoma years after thyroidectomy for presumed benign multinodular goiter.

Occult differentiated thyroid carcinoma may become clinically evident years after thyroidectomy performed for presumed benign multinodular goiter, presenting an important diagnostic challenge. Following CT-guided biopsy confirmation of metastatic differentiated thyroid carcinoma of thyroid follicular-cell origin, post-therapy ¹³¹I scintigraphy and SPECT/CT demonstrated multifocal iodine-avid pulmonary metastases and defined the functional extent of disease. These images illustrate the complementary value of post-therapy radioiodine imaging in characterizing iodine avidity and metastatic disease distribution.