False-positive Imaging for Papillary Thyroid Cancer Caused by Intraosseous Hemangiomas.

Two patients with papillary thyroid carcinoma and an elevated thyroglobulin had false-positive imaging studies from intraosseous hemangiomas (IH). A 62-year-old man presented with a palpable lytic skull mass suspicious for a bone metastasis after computed tomography (CT) and magnetic resonance imaging (MRI) scans. Surgical excision confirmed an IH. The second patient is a 64-year-old woman whose I-123 whole-body scan with single photon emission computed tomography/CT demonstrated radioiodine uptake in the right frontal bone. Her MRI and CT scans were also consistent with an IH. These cases reveal the limitations of nuclear imaging and of CT and MRI scans in distinguishing metastatic differentiated thyroid cancer from IH in patients with lytic bone lesions. Because no imaging studies are definitive for an IH, bone cranial lesions may warrant resection to establish a diagnosis and avoid potential brain invasion by a malignancy or unnecessary radioiodine treatment.