Iodine uptake in retroperitoneal cysts after radioactive iodine treatment

Radioactive iodine ablation has long-lasting effects on remnant thyroid tissue and metastasis from well-differentiated thyroid cancer. After radioactive iodine treatment, scintigraphy is a major imaging modality for detecting metastasis and assessing its management. False-positive iodine uptake can be found in many aberrant locations, including cysts. This report describes iodine uptake in retroperitoneal cysts in a 62-year-old woman diagnosed with papillary thyroid carcinoma. Radioiodine scintigraphy was performed after iodine therapy. Abnormally increased iodine activity was noted in the left upper abdomen. Additional radiologic examinations helped in preventing invasive biopsy.