Co-existent parathyroid adenoma and thyroid carcinoma. Nonspecificity of dual tracer parathyroid imaging for parathyroid lesions.

Dual tracer parathyroid imaging (DTPI) using Tc-99m and TI-201 has a reported sensitivity of 92% for the detection of parathyroid adenomas. A patient with biopsy-proven parathyroid adenoma as well as papillary thyroid carcinoma is presented. To date, this is the first such case ever to be reported and implies that DTPI, although a sensitive diagnostic modality for parathyroid adenoma detection, is not specific. The diagnosis of primary hyperparathyroidism has recently been established more frequently than in the past due to detection of elevated serum calcium levels on routine blood samples, relatively sensitive parathormone (PTH) assays, and noninvasive imaging modalities such as nuclear medicine, CT scanning, and ultrasonography. At our institution, we have successfully detected the location of parathyroid adenomas in many cases, using the dual tracer method with TI-201 and Tc-99m, confirmed at surgery. We present a case of primary hyperparathyroidism in which two distinct lesions were detected by nuclear imaging: one lesion was proven at surgery to be a parathyroid adenoma, while the other represented thyroid carcinoma.