Case presentations:

• Female.
• 75y.o.
• Virtually asymptomatic and previously submitted to thyroidectomybecause of multinodulargoiter (in 2004).
• Referred to Nuclear Medicine after surgical debulkingof a lumbar mass whose histology showed metastasis from welldifferentiated thyroid cancer.

Teaching points:

• Occult differentiated thyroid carcinoma (DTC) can be present in multinodulargoiter.
• DTCsare slow-growing and are usually treatable by combined surgery of the primary tumor, radio-iodine, and TSH-suppressive therapy.
• Tumor cell imaging with radioiodine (131I-or 123I-iodide) whole-body scan (WBS) is specific and sensitive for well differentiated DTC (especially if combined with TSHstimulated serum Tg assay).
• In selected instances, surgical debulking of metastatic lesions can be beneficial to patients.