Incidental Acinic Cell Carcinoma of the Parotid Gland Discordant on 123I-MIBG, 111In-Octreotide, and 18F-FDG PET/CT in a Patient With Neuroendocrine Tumor of the Cecum.

A 61-year-old woman diagnosed with a metastatic well-differentiated neuroendocrine tumor of the cecum was referred for radioisotope therapy. Although her metastatic neuroendocrine tumor was positive on both (123)I-MIBG and (111)In-octreotide, there was a left parotid mass that was octreotide avid but MIBG negative. Further investigation also showed discordance on (18)F-FDG PET/CT and excision of the mass revealed an incidental acinic cell carcinoma of the parotid gland. Somatostatin analog imaging and PRRT (peptide receptor radionuclide therapy) may have a role in the management of acinic cell carcinoma.