Medicina Nuclear e Radioterapia

Follicular Thyroid Carcinoma: A Tumor Histotype that Should Not be Underestimated

Abstract

Helga Castagnoli, Carlo Manni, Gloria Rossi, Sara Fattori and Francesca Capoccetti

Papillary and Follicular Differentiated thyroid carcinoma have a very good prognosis, such that survival in low-risk forms is comparable to a healthy person. However, the follicular thyroid carcinoma is typically more aggressive than the papillary one, so that in some patients the distant metastases represents the first clinical manifestation of the disease.

Although this is a rare condition, we can find asymptomatic distance metastases in the 18F-FDG PET/CT as “incidentalomas”, even in the absence of a primary tumor. This condition could be incorporated into the term occult thyroid carcinoma.

In patients with iodine avid metastatic differentiated follicular thyroid cancer, even if some metastatic lesions show pathological hypermetabolism to the 18F-FDG PET/CT scan, radioactive iodine therapy remains the treatment of choice. In this setting of patients the dosimetric study is mandatory.