The recent increase in the incidence of differentiated thyroid cancers has been reported worldwide, attributed to an overdetection of asymptomatic papillary microcarcinomas. Active surveillance has meanwhile emerged as a safe alternative to immediate surgery of microcarcinomas presenting with low-risk clinical, radiological, and cytological features. Given this cancer category, the risk of disease progression appears to be higher in third and fourth decades. Deferred surgical intervention has not been shown to modify disease recurrence and survival rates. A multidisciplinary approach proves to be critical for appropriate patient selection and follow-up.
The serendipitous detection, also called incidentaloma, of focal hypermetabolic abnormalities at 18F-fluorodeoxyglucose PET-CT of the thyroid gland is relatively frequent, estimated to be around 1.5-2% of the cases investigated. The prevalence of cancer cases appears to be very low, well below 1%. Considering that PET-CT is mainly performed in patients with –sometimes advanced- cancer, it is essential to refrain from extensive workups, with often limited impact as for the patient’s prognosis. To summarize, the work-up of focal abnormalities is similar to that of the usual workup of thyroid nodules, including rigorous ultrasound evaluation and, if deemed appropriate, fine-needle aspiration biopsy, as recommended by current guidelines. In patients with diffuse uptake, a general endocrinology workup, based on clinical and laboratory data, is recommended.
Excepting the presence of a compressive syndrome, there are no objective reasons for proposing a surgical resection exclusively based on size alone for large (3-4 or 5cm), cytologically benign nodules. A large size itself is neither a risk factor for malignancy nor does it result in a significantly larger number of false-negative results based on fine-needle aspiration cytology. Only a suspicious ultrasound appearance is likely to significantly increase the risk of false-negative results and should, in some cases, suggest performing either a new fine-needle aspiration cytology or diagnostic surgery.