Mucoepidermoid Parotid Gland Tumor Found on Follow-up Radioiodine Scan for Differentiated Papillary Thyroid Cancer.

This report presents a case of focal uptake in the right parotid gland found on a follow-up whole-body radioiodine scan 1 y after successful ablation of differentiated papillary thyroid carcinoma. After the parotid tumor had been excised, it was proven histopathologically to be a low-grade mucoepidermoid tumor. This case illustrates a 131 I focus that was false-positive for thyroid carcinoma. The short period between radioiodine treatment and development of this parotid tumor creates doubt about a causal relationship. Induction of salivary gland tumors by radiation has been reported primarily in the setting of external radiotherapy. In the large volume of thyroid carcinoma patients treated with radioiodine across the world, such an occurrence has been rare.