Non-Invasive Follicular Thyroid Neoplasm with Papillary-Like Nuclear Features: Pitfalls of Cytological and Histopathologic Diagnosis

Abstract

Classical papillary thyroid carcinoma (PTC) is the commonest primary thyroid neoplasm. Besides PTC, significant histological variants that differ from classical PTC in regard to the morphological, cytologic and histologic features are mentioned; among them is follicular variant papillary thyroid carcinoma (FVPTC). The update WHO classification and the update Bethesda system reclassified FVPTC introduced a new entity which is "non-invasive follicular thyroid neoplasm with papillary like nuclear features" (NIFTP) that is characterized by an indolent behavior with encapsulated noninvasive growth features. Recently this entity is considering one of an indeterminate cytological categories (category III-IV-V). Update studies are found a combination of triple diagnostic procedures included sonographical, cytologic and molecular investigations can be suspecting preoperative diagnosis. Methods: A total of 150 selected cases of solitary thyroid nodules (STNs) with preoperative FNAC have an indeterminate follicular patterned cytological lesions with their underlying thyroidectomies that were collected in a 5-year period included in this article. Results: Majority of our cases were females and suffering from neck swelling. Cytollogically all the enrolled cases were lying in the indeterminate categories and histologically they were encapsulated with variable sizes follicles, nuclear features, no vascular invasion, no psammoma bodies, no tumor necrosis or mitosis. Also, there is no any extra-thyroid invasion. Conclusion: The accurate diagnosis of this entity “”NIFTP” carries many congratulations in regard that is “not malignant” category among both update TBSRTC and the final histopathological examination of the excised thyroid tissue.