Indeterminate thyroid nodules (TIR3A/TIR3B) according to the new Italian reporting system for thyroid cytology: A cytomorphological study

Abstract

Objective: The Italian reporting system for thyroid cytology classifies indeterminate lesions as TIR3A (low risk) or TIR3B (high risk) and is meant to provide practical guidance rather than a detailed consideration of morphological features. We aimed to assess which cytological features have the most diagnostic value and whether they are effective in classifying nodules as either TIR3A or TIR3B and in predicting histological outcomes.Methods: Thyroid fine-needle aspirates from 111 indeterminate nodules were reviewed blinded to clinical information, TIR3A/TIR3B classification, and histology in order to assess which cytological features (pooled into artefacts, smear background, architectural and nuclear atypia, and oncocytes) differentiate TIR3A from TIR3B, and benign from malignant histological outcomes. Results:Of the cytological features examined, those specific for TIR3B included high cellularity, nuclear atypia, oncocyte predominance and transgressing vessels.Features specific for TIR3A included artefacts, low cellularity and oncocyte sparseness. Other features, such as microfollicules/trabeculae, were non-specific. Due to the different distributions of these features, three TIR3B subgroups were identifiable: follicular lesions with oncocytic changes, pure follicular lesions, and follicular lesions with nuclear atypia, whereas no subgroups were identifiable in TIR3A. Nuclear atypia was a significant indicator of malignancy, whereas oncocyte predominance was not a reliable predictor of malignancy. High cellularity and microfollicules/trabeculae were not indicative of any histological outcome. Conclusions:The majority of the assessed features were good predictors of histological outcomes. The TIR3A category included undefined nodules due to the absence of characterising features, whereas the TIR3B category included nodules with a greater number of distinguishing features. K E Y W O R D Sclassification, cytopathology, Italy, thyroid cancer, thyroid nodule

Predictive factors of malignancy in pediatric patients with thyroid nodules and performance of the Italian classification (SIAPEC 2014) in the outcome of the cytological FNA categories

“…We compared the data of our study with the results of similar studies on Italian adult cohorts and the main studies on pediatric cohorts based on the BSRTC classification (Table 5) [32][33][34][35][36][37][38][39][40][41][42][43][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59]. Italian studies based on the 2014 SIAPEC classification report an average malignancy rate of 14.2% for TIR3a nodules and 44.7% for the TIR3b cytological category in studies with adult cohorts [32][33][34][35][36][37][38][39][40][41][42][43]. In our cohort, we did not observe any malignancy among TIR3a nodules but the amount of histological data was very small, although the follow-up of 4.6 years confirmed the cytological category in all subjects who performed clinical follow-up with FNAB repeated every 12-18 months.…”

“…For the adult population, some Italian authors have studied national cohorts affected by thyroid nodules and reported significantly higher sensitivity of the Italian system than the Bethesda one, validating the TIR3a/TIR3b subclassification for the individuation of benign nodules and malignant tumors, with a ROM of 4-20.8% and 28-60.3%, respectively [32][33][34][35][36][37][38][39][40][41][42][43]. Pediatric studies based on the BSRTC system indicate a higher ROM for indeterminate nodules (39.5% for AUS/FLUS category [44] and 41.5% for the SFN category) compared to adults (30.5 and 28.9% respectively), with no substantial differences in ROM between the two indeterminate categories in both pediatric and adult age [45][46][47][48][49][50][51][52][53][54][55][56][57][58].…”

“Predictive Factors of Malignancy in Pediatric Patients with Thyroid Nodules and Performance of the Italian Classification (SIAPEC 2014) in the Outcome of the Cytological FNA Categories”

“…We compared the data of our study with the results of similar studies on Italian adult cohorts and the main studies on pediatric cohorts based on the BSRTC classi cation (Table 5) [33][34][35][36][37][38][39][40][41][42][43][44][46][47][48][49][50][51][52][53][54][55][56][57][58][59][60]. Italian studies based on the 2014 SIAPEC classi cation report an average malignancy rate of 14.2 % for TIR3a nodules and 44.7% for the TIR3b cytological category in studies with adult cohorts [33][34][35][36][37][38][39][40][41][42][43][44]. In our cohort we did not observe any malignancy among TIR3a nodules but the amount of histological data was very small, although the follow-up of 4.6 years con rmed the cytological category in all subjects who performed clinical follow-up with FNAB repeated every 12-18 months.…”

“…For the adult population, some Italian Authors have studied national cohorts affected by thyroid nodules and reported signi cantly higher sensitivity of the Italian system than the Bethesda one, validating the TIRa/TIR3b subclassi cation for the individuation of benign nodules and malignant tumors, with a rate of malignancy of 4-20.8% and 28-60.3%, respectively [33][34][35][36][37][38][39][40][41][42][43][44]. Pediatric studies based on the BSRTC system indicate a higher ROM for indeterminate nodules (39.5% for AUS/FLUS category and 41.5% for the SFN category) compared to adults (30.5% and 28.9% respectively), with no substantial differences in ROM between the two indeterminate categories in both pediatric and adult age [46][47][48][49][50][51][52][53][54][55][56][57][58][59].…”

The diagnostic accuracy of fine-needle aspiration cytology for thyroid nodules is not affected by coexistent chronic autoimmune thyroiditis: results from a cyto-histological series of patients with indeterminate cytology

“…Thus, at present, the clinical management of thyroid nodules with indeterminate cytology still represents an unresolved issue. Despite the well-known role of clinical aspects on the decision making for patients with indeterminate cytology, the possible influence of specific clinical features on the cytological findings and hence on the indeterminate cytological reports has not been fully investigated so far (6,7). Unfortunately, to date, there is no pre-operative gold standard for accurately predicting the risk of malignancy of a cytologically indeterminate nodule (6,7,8,9,10).…”