False-Positive Tc-99m Sestamibi Examination for Parathyroid Adenoma in a Case of Asymmetrical Salivary Gland Enlargement

A 50-year-old African American man with multiple endocrine neoplasia type I and Zollinger-Ellison syndrome had a Tc-99m sestamibi scan as part of an evaluation for parathyroid adenoma-hyperplasia. His history was positive for multiple gastric and duodenal ulcers. Biochemical parameters for hyperparathyroidism were equivocal; borderline parathyroid hormone elevation was present with low phosphate but normal calcium levels. An abnormal focus of radioactivity was evident in the right neck region in the area of the carotid bifurcation. A CT scan was obtained before contemplated neck exploration. Marked asymmetry of the right submandibular gland, corresponding to the focus of tracer uptake, was present with virtual absence of the left gland. The patient subsequently died of pulmonary embolism on the 25th day after surgery for pancreatic and duodenal neuroendocrine tumors. Post mortem examination confirmed an enlarged right submandibular gland with normal thyroid and parathyroid glands.