Abstract
We report herein ten cases of primary hyperparathyroidism (pHPT) caused by intrathyroid parathyroid adenoma (IPA). Of the 319 patients who underwent parathyroidectomy for pHPT between April 2006 and December 2013, ten patients (3.1%) were found to have IPAs (eight in the right lobe and two in the left lobe) by pathological examination. Six patients were found to have IPAs in the lower pole of the thyroid. Under ultrasonography, IPA showed a hypoechoic mass in seven patients, an isoechoic mass in two, and a mixed pattern mass in one. Six patients showed hypervascularity in IPA under color Doppler ultrasonography. MIBI scintigraphy showed accumulation of the isotope in ITA in five of the seven patients examined. CT was able to point out an intrathyroid nodule, but the qualitative diagnosis was difficult. We could confirm preoperatively the intrathyroid nodule to be a pathological parathyroid tumor in five of the six patients, by measuring PTH concentration of the aspirate obtained from the nodule under ultrasonography. Preoperative jugular venous sampling with PTH analysis was also useful to localize the laterality of pathological ITA in one patient.
