Introduction: Radioactive iodine (RAI) for remnant ablation and post RAI scanning are very frequently employed modalities in differentiated thyroid cancers (DTC). Radioactive iodine is secreted into physiological secretions such as tears and urine. In this case report we present a case who received RAI for DTC with a surprising post RAI scan compatible with multiple metastases.
Case report: A 53-year-old male subject underwent total thyroidectomy and ipsilateral lymph node dissection after being diagnosed as papillary thyroid cancer (PTC) via fine needle aspiration cytology (FNAC). He received 150 mCI of RAI due to lymph node metastases. His stimulated thyroglobulin level (Tg) was 33.3 ng/ml and was positive for anti thyroglobulin antibodies. In the post RAI scan we visualized suspicious metastases in the thyroidal area together with the mid abdominal, proximal right femoral, mid left femoral and distal left tibia areas. The metastatic findings were untypical and were localized anteriorly. Also the patients general situation was fine so we planned a bone scan and PET CT to confirm these findings. Both bone scans and FDG PET was negative for metastases. The subjects socioeconomic status and personal hygiene was very low thus we suspected these findings were secondary to urine contamination. Six months later he underwent a whole body scan which was negative for metastases. His stimulated Tg was 1.16 ng/ml and anti Tg was positive during the scan.
Discussion: Post RAI scanning is a very important technique for determining metastases in subjects with DTC. Contamination with body fluids can cause false metastatic findings in which other radiological methods and personal history can aid the physicians in making a decision.