Serendipitous detection of metastatic thyroid cancer during I-123 Tc-99m sestamibi dual parathyroid imaging.

Dual isotope parathyroid imaging performed on a 47-year-old man with known papillary thyroid cancer and biochemical hyperparathyroidism showed residual concentration of sestamibi consistent with a right inferior parathyroid adenoma. Subsequent thyroidectomy and parathyroidectomy was performed. Histology revealed a left superior parathyroid adenoma and normal right inferior parathyroid gland. Right inferior parathyroid adenoma on scintigraphy was, in fact, a cervical lymph node metastasis from the papillary thyroid carcinoma.