LAUSR

Dear Editor, Recently, the noninvasive encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC) received the name “noninvasive follicular thyroid neoplasm with papillary-like nuclear features” (NIFTP) and was no longer considered “cancer.” Furthermore, the treatment recommendations for differentiated thyroid cancer no longer apply to NIFTP, which is sufficiently treated by lobectomy only. The probability that a thyroid nodule corresponds to NIFTP has become of great interest in clinical practice since it would at least influence the extent of surgery. Thus, several studies have been dedicated to defining the preoperative characteristics of NIFTP. Some studies have shown that the evaluation of glucose uptake by 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) helps differentiate between benign and malignant nodules. To our knowledge, there are no studies characterizing NIFTP in terms of glucose uptake. Since fine-needle aspiration (FNA) is not recommended for nodules <1 cm without apparent extrathyroid invasion and nodules >1 cm with indeterminate cytology and a high clinical or ultrasonographic suspicion of malignancy are direct candidates for surgery, FDG-PET was requested by us for nodules >1 cm with indeterminate cytology (according to the Bethesda System, category III or IV) without a high clinical or ultrasonographic suspicion of malignancy. During the phase of evaluation of these nodules by FDG-PET, all patients submitted to this imaging method were subsequently referred for surgery for correlation with histology. We report here the results of nodules finally diagnosed as NIFTP (n58) and invasive/infiltrative FVPTC (n54). Only 1/8 NIFTP (12.5%) did not exhibit uptake of FDG, while in 7/8 nodules (87.5%) uptake of FDG was clearly higher than in the thyroid parenchyma (positive FDG). SUVmax was 2 in 7/8, 5 in 5/8, and >5 in 2/8 (25%). In FVPTC, 4/4 nodules (100%) were FDGpositive. SUVmax was 2 in 4/4, 5 in 1/4, and >5 in 3/4 (75%). The results of the 12 patients are shown in Table 1. Although the confirmation in larger studies is necessary, these preliminary data suggest that NIFTP exhibits an increase in glucose uptake compared to the normal thyroid, a characteristic that is closer to that