Non-invasive Follicular Thyroid Neoplasm with Papillary-like Nuclear Features and the Practice in Qilu Hospital of Shandong University, China

Non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) was introduced to cover a group of non-invasive encapsulated follicular-patterned thyroid lesions with very low malignant behavior. This nomination may have a great impact on the incidence of thyroid malignancy and the practice for endocrine pathologists. To demonstrate the proportion of the thyroid follicular cell-originated malignancy and the incidence of NIFTPs in China, the surgical samples during the period of 2007 to 2016 were reviewed by three pathologists in Qilu Hospital, China. There were 5561 cases of thyroid malignancies in total and 5412 of them were papillary thyroid carcinoma (PTC). Of the PTC, 132 were proved to be follicular variant of papillary thyroid carcinoma (FVPTC) (including three subtypes: non-encapsulated infiltrative, encapsulated invasive, and encapsulated non-invasive), and only 20 (0.37% in all PTCs and 0.23% in all thyroid malignancies) were diagnosed as NIFTP. Therefore, only a very small proportion of NIFTP was observed and it is expected to have only minor or negligible impact on the incidence of thyroid malignancy in the practice at Qilu Hospital.