[Hyperparathyroidism and intrathyroid parathyroid gland. 43 cases]

The rate of occurrence of intrathyroidal parathyroid glands in patients treated surgically for hyperparathyroidism (HPT) varies across studies. Among 1200 consecutive patients who underwent surgery for HPT at the Lille Hospital, France, between December 1965 and July 1992, 43 (3.6%) had 47 histologically-proven intrathyroidal parathyroid glands, including 44 lower and three upper parathyroid glands. Fifteen patients had a thyroid gland abnormality. Of the 14 patients who had a preoperative ultrasound study, eight exhibited an abnormal image. Thirty-four of the 47 intrathyroidal parathyroid glands were visible at the surface of the thyroid gland, five were felt on palpation, and eight were discovered upon examination of a lobectomy specimen. A normal or abnormal parathyroid gland can be completely concealed within the thyroid gland, even in the absence of concomitant thyroid gland disease. In most cases, the ectopia affects one or both lower parathyroid glands, although in some instances the two glands on the same side are intrathyroidal. There is no fail-proof means for detecting intrathyroidal parathyroid glands preoperatively. An apparently missing fourth parathyroid gland or a fifth gland should be looked for in the thyroid gland when the cause of HPT is not found during a first cervicotomy procedure. Pre- or intra-operative ultrasonography may be the most informative imaging method for detecting intrathyroidal parathyroid glands and should be performed routinely when a repeat procedure for persistent HPT is being considered.