Concomitant hyperparathyroidism and nonmedullary thyroid cancer, with a review of the literature.

PURPOSE: Primary hyperparathyroidism and concomitant thyroid cancer is a rare and complicated setting for diagnostic imaging.
MATERIALS AND METHODS: The authors report the accidental finding of primary hyperparathyroidism in a patient with rapid enlargement of a thyroid nodule and the results of a literature review.
RESULTS: Tl-201-Tc-99m subtraction scintigraphy correctly revealed the malignant nature of a large cold thyroid nodule and mediastinal parathyroid hyperplasia. In contrast, high-resolution ultrasound indicated a retrothyroidal hyperplastic parathyroid gland. Surgery followed the findings of the preoperative ultrasound and intraoperative biopsy, yet hyperparathyroid disease persisted. Repeated scintigraphy confirmed an ectopic parathyroid gland, which was resected from a paraesophageal location. Subsequently, hormone and calcium levels returned to normal and remained normal during a follow-up period of 3 years. A literature review revealed a prevalence of approximately 3% of nonmedullary thyroid cancer, which was found in patients operated on for primary hyperparathyroidism. Previous neck irradiation, especially in childhood, appears to be a risk factor for the development of both nonmedullary thyroid carcinoma and for primary hyperparathyroid disease.
CONCLUSIONS: This case illustrates the need for clinical awareness of concomitant hyperparathyroidism and nonmedullary thyroid cancer and is substantiated with published case reviews. The preoperative scintigraphic localization of hyperfunctioning parathyroid tissue, although not advised as a routine procedure, may provide diagnostic information in addition to high-resolution ultrasound and intraoperative biopsy. In addition, scintigraphy can be useful even in the technically difficult setting of concomitant thyroid cancer.