We herewith report an unusual case of primary hyperparathyroidism whose parathyroid adenoma strongly accumulated technetium (Tc)-99m pertechnetate. A 41-yearold woman was referred to our department under the tentative diagnosis of primary hyperparathyroidism. Scintigraphy by thallium-201 chloride showed homogeneous uptake in the whole thyroid, whereas Tc-99m image revealed a strong local accumulation in the middle portion of the right thyroidal lobe. Neck exploration revealed a 12×8×5-mm tumor in the posterolateral region of the right thyroidal lobe, the pathology of which was parathyroid adenoma. In addition, a small nodule (8 mm in diameter) with pathological findings revealing follicular adenoma of the thyroid, was found within the medial portion of the right thyroidal lobe. Both lesions were removed by surgery, and a postoperative Tc-99m scintigraphy no longer demonstrated a significant uptake in the right thyroidal lobe. Since the thyroid adenoma was too small to be detected by any scintigraphic study and located much closer to the median line than the site of the marked accumulation of Tc-99m pertechnetate, it was considered very likely that the parathyroid adenoma concentrated Tc-99m. Search of literature revealed that there have been only thirteen cases of parathyroid tumor reported to date which significantly accumulated Tc-99m pertechnetate. The present patient represents another rare case of parathyroid adenoma showing such an unusual scintigraphic image.
(Internal Medicine 40: 506-509, 2001)