Differential tumor biology between locoregional and distant metastasis in a patient with TENIS with TKI-resistant aggressive recurrent disease: a comparative evaluation with FDG, ⁶⁸Ga-DOTATATE and ⁶⁸Ga-PSMA-11 PET-CT

Abstract

The molecular PET-CT imaging profile of an interesting case of differentiated thyroid carcinoma, later transformed into with thyroglobulin elevation and negative iodine scintigraphy (TENIS) with tyrosine kinase inhibitor (TKI) resistant recurrent aggressive disease, is presented. The patient was evaluated to assess SSTR-2 or PSMA expression to explore the possibility of any effective targeted nuclear therapy. ¹⁸F-FDG, ⁶⁸Ga-DOTATATE and ⁶⁸Ga-PSMA-11 PET/CT was performed, which revealed tracer avidity in all 3 scans in the extensive loco-regional disease of large ill-defined retropharyngeal and retro-tracheal soft tissue eroding cricoid cartilage, extending into tracheal lumen and left sided strap muscles. On the contrary, there was no definite uptake in the multiple bilateral lung nodules, the scan findings indicating a differential tumor biology between loco-regional and distant metastasis.