False-Positive Parathyroid Sestamibi in Minimally Invasive Radioguided Parathyroidectomy

ABSTRACT

A (99m)Tc-sestamibi scan has become the most widely used localizing test for identifying a parathyroid adenoma. Despite its popularity, the effectiveness of (99m)Tc-sestamibi scan for parathyroid localization is still controversial due to the large number of false-positive results. The false positive (99m)Tc-sestamibi scan can be attributed to a thyroid adenoma, nodular hyperplasia, metastatic thyroid cancer and other proliferating thyroid diseases because (99m)Tc-sestamibi is specific to the mitochondrial membrane of cells with high-level metabolic status, and not specific to the parathyroid itself. Minimally invasive radio-guided parathyroidectomy (MIRGP) was performed on a 61 year-old woman. The (99m)Tc-sestamibi focus was completely excised with gamma-probe guidance. However, the frozen pathology showed the excised tissue to be a thyroid papillary carcinoma. We present the unexpected false-positive (99m)Tc-sestamibi in MIRGP, and discuss the considerations in order to reduce the number of false-positive parathyroid (99m)Tc-sestamibi scans.