Triple Tracer Heterogeneity in Dual Neoplasia: The "Three Musketeers" in Discerning Squamous Cell Carcinoma and Paraganglioma in the Same Patient

Head and neck squamous cell carcinoma of unknown primary (HNSCCUP) comprises 2%-5% of head and neck squamous cell cancers (HNSCC). Its coexistence with abdominal paraganglioma is exceedingly rare. We report a unique case of a 48-year-old male with HNSCCUP presenting as cervical lymphadenopathy and a coexisting abdominal paraganglioma. 18 F-FDG showed uptake in both lesions, while 68 Ga-DOTATATE was avid only in paraganglioma, and 68 Ga-DOTA-FAPI-04 was avid only in cervical nodes. These differential uptake patterns reflect distinct tumor biology and underscore the potential for tailoring theranostic treatment strategies with 177 Lu/ 90 Y isotopes for FAPI-avid squamous cell cancers (SCC) and DOTATATE-avid paragangliomas.