Marta Argelés Colet, Viviana Carrero Vasquez, María Pilar Perlaza Jimenez, Elena Llinares Tello, Alba Rodríguez Gasen, Andrea Isidora Fritsch Medina, Montserrat Cortés Romera
Anaplastic thyroid carcinoma (ATC) is an aggressive malignancy associated with poor survival and a metastatic pattern that typically involves the lungs. A patient with ATC harboring a papillary component and a BRAF V600E mutation, with locoregional invasion, was treated with surgery and radiotherapy following detection of residual disease. After a disease-free interval of 17 months, a lesion was identified at the splenic flexure of the colon, which was histologically confirmed as a metastasis from ATC. This case demonstrates an unusual metastatic site and emphasizes the value of [¹⁸F]FDG PET/CT in detecting atypical recurrences.