Parathyroid Adenoma at the Parapharyngeal Space Detected on 99mTc-Sestamibi SPECT/CT

A 77-year-old woman was diagnosed with primary hyperparathyroidism, and initial cervical ultrasonography found no parathyroid lesion, and she was referred to the nuclear medicine unit for dual-phase 99m Tc-sestamibi (MIBI) scan. The scintigraphy unveiled heterogeneous uptake patterns across bilateral thyroid lobes, corresponding to the thyroid nodules, alongside a marked focal uptake with delayed tracer washout in the right oral region. The SPECT/CT pinpointed a MIBI-avid nodule within the right parapharyngeal space, indicative of parathyroid ectopia. An ectopic parapharyngeal parathyroid adenoma is exceptionally rare. MIBI scan plays a pivotal role in detection of ectopic parathyroid adenoma at unexpected sites.