Noninvasive follicular neoplasm with papillary like nuclear features: A comprehensive analysis with a diagnostic algorithm.

Abstract

Noninvasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP) lacks the carcinoma label, avoiding aggressive therapy, physiological, social and financial impact of cancer diagnosis. Unfortunately, the preoperative diagnosis is still a challenge. Varied incidence of NIFTP has been document with limited data on preoperative cytological, radiological characteristics and the impact on risk of malignancy in each category of the Bethesda system of reporting thyroid cytopathology. Retrospective analysis of 20 NIFTPs with an attempt to provide a preoperative diagnostic algorithm based on the cytological and ultrasound features along with incidence and implication on risk of malignancy in various Bethesda categories with its impact on patient management. Incidence of NIFTP in our study was higher in comparison to that documented from other Asian countries. TIRADS 3 was the most common sonographic diagnosis. NIFTP was commonly preceded by indeterminate or benign Bethesda category. Major impact of excluding NIFTP form malignant category was seen on Bethesda categories II and IV with 20% and 27% reduction in risk of malignancy, respectively. Retrospective analysis should not be confined only to follicular variant of papillary thyroid carcinoma but cases of follicular adenoma and adenomatous colloid nodule should always be included in review to ascertain the true incidence of NIFTP. NIFTPs are less likely to have malignant preoperative cytology. NIFTP shares major cytological and ultrasound features with follicular adenoma, adenomatous colloid nodule and minimally invasive follicular papillary carcinoma. When analyzed together, taking minor findings in consideration, can favor a diagnosis.