The major goals of the introduction of the noninvasive follicular neoplasia with papillary-like nuclear features (NIFTP) are to spare patients with a biologically indolent subgroup of the follicular variant of papillary carcinoma (FV-PTC) both overtreatment and the psychologically burden of a cancer/carcinoma diagnosis. However, strict histological and molecular pathological criteria have been introduced for the diagnosis of NIFTP. NIFTP tumors may be a few millimeters in diameter, but may also measure more than 4 cm. Histologically, an encapsulated/clearly demarcated lesion with (>70%) follicular structure and the nuclear characteristics of PTC must be present as a prerequisite; invasion of capsule/vessels must be excluded as well as significant proportions (>30%) showing a solid/trabecular/insular growth pattern, psammoma bodies, tumor necrosis, an increased mitotic rate (>3/10 HPF), and/or a BRAF V600E mutation. The establishment of the NIFTP necessitated a redefinition of the diagnostic criteria of PTC and has implications on the evaluation of fine needle biopsy (FNB) of the thyroid gland. Although a prediction is difficult, the correct diagnosis of NIFTP could lead to a 10-20% reduction in thyroid carcinoma incidence.
Keywords: Fine-needle biopsy; Molecular pathology; Overtreatment; Papillary carcinoma; Thyroid neoplasms.