Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) in thyroid tumor classification.

Kakudo K, El-Naggar AK, Hodak SP, Khanafshar E, Nikiforov YE, Nosé V, Thompson LDR.
Pathol Int. 2018 Apr 19. doi: 10.1111/pin.12673. [Epub ahead of print]
In 2016, a new morphological thyroid tumor entity, noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP), was introduced to replace a group of lowrisk tumors known as noninvasive encapsulated follicular variant of papillary thyroid carcinoma (EFVPTC). Since then, there have been more than 60 publications with a keyword of NIFTP according to a PubMed literature survey on October 28, 2017. These publications cover many aspects on this new tumor entity, cytological diagnosis, ultrasound features, molecular genotyping, clinical management and long-term outcome of NIFTP patients. They supported an indolent nature of NIFTP even in large size (>4 cm) tumors. Under ultrasound examination, NIFTPs are usually in low-suspicion nodules while invasive EFVPTC in intermediate-suspicious nodules and infiltrative FVPTCs in high-suspicion nodules. In FNA cytology, the majority of NIFTP are classified in indeterminate (atypia of uncertain significance/follicular lesion of uncertain significance, follicular neoplasm/suspicious for follicular neoplasm or suspicious for malignancy) categories. The new 4th edition of the World Health Organization (WHO) Classification of Tumours of Endocrine Organs including thyroid tumors was published in 2017 and it incorporated a new chapter on borderline tumors of follicular cell origin. These included hyalinizing trabecular tumor, uncertain malignant potential (UMP), and noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). UMP and NIFTP were incorporated as subchapters in a new chapter of other encapsulated follicular-patterned thyroid tumors (Table 1). Their behavior codes were set as /1 (unspecified, borderline, or uncertain behavior), and not /0 (benign tumors), /2 (carcinoma in situ and grade III intraepithelial neoplasia), or /3 (malignant tumors).
This editorial was written by seven authors, on behalf of all authors of the NIFTP working group, to refine diagnostic criteria for NIFTP in order to improve concordance in the diagnosis and to address several issues with the diagnosis of NIFTP raised in recent publications.
PubMed ID: 29675873
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