99m Tc-FAPI-46 Scintigraphy in Parotid Mucoepidermoid Carcinoma.

We report a 58-year-old woman with recurrent mucoepidermoid carcinoma (MEC) of the right parotid gland who developed progressive, refractory bone pain following surgery and adjuvant radiotherapy. A 99m Tc-MDP bone scintigraphy demonstrated limited skeletal metastases, and palliative radiotherapy failed to alleviate symptoms. Amid worsening and more widespread bone pain accompanied by cough and hemoptysis, a 99m Tc-FAPI-46 scintigraphy revealed multiple skeletal metastases, pulmonary involvement and metastatic lymph nodes, showing a markedly greater disease burden. This case highlights the potential added value of FAP-targeted imaging in detecting metastatic disease extent in MEC and suggests that 99m Tc-FAPI-46 may provide comprehensive information beyond conventional imaging, particularly in patients with discordant symptoms and imaging findings.