Uncommon metastases from differentiated thyroid carcinoma.

Differentiated thyroid carcinoma (DTC) usually behaves in an indolent manner with low metastatic potential. The major sites of distant metastases are the lung and bone. Metastases to the brain, eye, breast, liver, kidney, muscle and skin are rare or relatively rare. These metastases have almost always appeared in patients with advanced disease and are often associated with poor prognosis but overlooked in clinical practice. Recognizing them has a significant impact on clinical decision-making and prognosis of the patients. Treatment in these patients should be individualized and an alternative therapeutic approach should be considered. Care should be taken to determine whether a (131)I uptake focus found at an unexpected site of (131)I- whole body scan (WBS) is a DTC metastasis or a false-positive (131)I uptake. Imaging with (131)I-SPET/CT is of incremental value in the finding of rare metastases from DTC. In conclusion, DTC can have unusual metastatic presentations and patterns. Post-therapy (131)I-WBS and (131)I-SPET/CT play an important role in the management of patients with DTC.