Subcategorization of atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS): a study applying Thyroid Imaging Reporting and Data System (TIRADS)

Abstract

Suspicious US features are useful in predicting malignancy among AUS subcategories but not in FLUS subcategories. Subcategorization into AUS and FLUS cytology may be helpful in deciding upon treatment or management of thyroid nodules.

The predictive value of sonographic images of follicular lesions – a comparison with nodules unequivocal in FNA – single centre prospective study

“…Yoon et al [10] found significant differences in TIRADS category between benign and malignant nodules in the AUS subgroup, but not in the FLUS subgroup. In the group of nodules with FLUS in cytological result PTCs amounted to 57% of malignant neoplasms while in the AUS group - 100%.…”

“…Among others, the usefulness of classic ultrasonography is evaluated in the selection of nodules for fine-needle aspiration biopsy (FNA) or in assisting clinical decision making in patients with equivocal FNA results – mainly in patients with follicular lesions (FL) [1–10]. …”

“…Particular discrepancies regard effectiveness of the analysis of sonographic features to estimate risk of malignancy in two categories of FL: follicular lesion of undetermined significance - FLUS –group III of cytological diagnoses in the Bethesda system and suspicious for follicular neoplasm – SFN –group IV of cytological diagnoses [1, 2, 7, 10, 14–19]. For the patients with FLUS in cytological outcome this issue is of particular importance, as this result has not been established as a direct indication for surgical treatment [11, 20].…”

Cytomorphologic, Imaging, Molecular Findings, and Outcome in Thyroid Follicular Lesion of Undetermined Significance/Atypical Cell of Undetermined Significance (AUS/FLUS): A Mini-Review

“…TIRADS has a very similar approach to the Breast Imaging Reporting and Data System (BIRADS) classification and correlates with increasing the ROM of focal lesions in six cytologic categories. Suspicious features of TIRADS are solid structure, low or very low echogenicity, irregular or microlobular borders, microcalcifications, and vertical shape (TIRADS 3 = no suspicious features; TIRADS 4a = 1 suspicious feature; TIRADS 4b = 2 suspicious features; TIRADS 4c = 3 or 4 suspicious features; TIRADS 5 = 5 suspicious features) [74-76]. The Mayo Clinic scoring system is considered an ultrasonographic diagnostic system including the three categories “almost certainly benign,” “indeterminate,” and “worrisome.” The criteria for being worrisome are the same, i.e., microcalcification, solid components, and irregular margin[77].…”

Thyroid ultrasonography for personalized approach at thyroid nodules

“…According to TBSRTC, follow-up FNA is recommended for nodules with nondiagnostic or atypia of undetermined significance/follicular lesion of undetermined significance results and clinical follow-up is recommended for nodules with benign results. However, these nodules have different cancer risks according to their US features [8][9][10]. For nondiagnostic nodules, follow-up can be recommended when there are no suspicious findings on US [8].…”