Ectopic Parathyroid Adenoma of the Piriform Sinus on Parathyroid 4D-CT and 99mTc-MIBI SPECT/CT.

Ectopic parathyroid adenomas are a common cause of postsurgical persistent primary hyperparathyroidism. Our case highlights a patient with a negative bilateral 4-gland exploration with follow-up parathyroid 4-dimensional CT and Tc-MIBI SPECT/CT, yielding focal uptake in the right piriform sinus. Subsequent direct laryngoscopy revealed a mass in the piriform sinus, which was resected with surgical pathology yielding parathyroid adenoma.