Triple Tracer Heterogeneity in Dual Neoplasia

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. 18F-FDG showed uptake in both lesions, while 68Ga-DOTATATE was avid only in paraganglioma, and 68Ga-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 177Lu/90Y isotopes for FAPI-avid squamous cell cancers (SCC) and DOTATATE-avid paragangliomas.