I-131 false positive uptake in a huge parapelvic renal cyst

A male patient had undergone total thyroidectomy for thyroid papillary carcinoma. He was administered thyroablation activity of radioiodine. Whole body imaging after diagnostic activity of 131-I demonstrated intense radioiodine uptake in the right side of the upper abdominal region. The serum thyroglobulin level was low. Ultrasonography demonstrated a large irregular anechoic structure in the centre of the right kidney - a cyst in the para pelvic region. Renal cysts can lead to erroneous interpretation of radioiodine scintigraphy. (authors)