Abstract:
Objective: To investigate the clinicopathological features of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP).
Methods: From January 2012 to December 2017 in First Affiliated Hospital of Bengbu Medical College, the clinical manifestations, histomorphology, immunohistochemistry, molecular genetics, and prognosis of 7 cases with NIFTP were retrospectively reviewed, along with the relevant literature.
Results: Of the 7 NIFTP cases, 4 were females and 3 males. The age of onset ranged from 36 to 54 years (median 50 years). The tumor diameters ranged from (0.2-3.0) cm (median 1.2 cm). Solitary nodules were found in 4 cases, double nodules in 2 cases and multiple nodules in 1 case. In all 7 cases, the capsule was intact, the boundary was clear, and there was no vascular and capsule infiltration. The nucleus of the tumor was large and crowded. Some nuclear sulci, nuclear pseudo inclusion bodies, and ground glass-like nuclei could be seen, which had the nuclear characteristics of papillary thyroid carcinoma. Lacking of tissue-specific expression, diagnosis value of immunohistochemical staining was limited. The proliferation index of Ki-67 was low. Two cases of KRAS and NRAS gene mutations were detected by quantitative fluorescence polymerase chain reaction, but no BRAFV600E mutations were found. During the follow-up period of 21 to 74 months, 5 cases displayed no recurrence or metastasis, and 2 cases were lost to follow-up.
Conclusions: NIFTP is a borderline thyroid tumor with very low malignant potential. It has specific morphological manifestations and inert biological behavior. Detection of the RAS gene mutation is helpful for the diagnosis of NIFTP.