Use of molecular testing results to analyze the overuse of atypia of undetermined significance in thyroid cytology

INTRODUCTION

The suggested atypia of undetermined significance (AUS) rate for thyroid fine-needle aspiration biopsies is 10% or less. Prompted by a high institutional AUS rate, we examined using molecular testing results (MTR) as a potential quality metric tool to reduce the AUS rate. We correlated MTR with AUS cytologic findings, surgical pathology follow-up, and individual pathologist AUS rates.

MATERIALS AND METHODS

Demographic data, cytologic diagnoses, MTR, and surgical pathology diagnoses were retrospectively obtained. MTR were classified as either positive or negative. AUS rates and MTR proportions were compared among pathologists. The cytomorphologic features of 143 AUS cases were assessed and correlated with MTR.

RESULTS

Between 2017 and 2022, 710 of 3247 thyroid fine-needle aspirations were classified as AUS, with a yearly average rate of 22% (range = 19%-26%). AUS cases included: 331 (47%) with architectural atypia; 204 (29%) with oncocytic (Hürthle cell) atypia; 99 (14%) with combined architectural and cytologic atypia; and 76 (10%) with isolated cytologic atypia. Most AUS cases with molecular testing had negative MTR (360/492, 73%). AUS with cytologic atypia had higher positive MTR risk (logarithm of odds ratio = 1.27, 95% credible interval [0.5-2.04], P = 0.001). The average positive MTR rate by pathologist was 21.5% (range 0%-35%); higher positive MTR rates had better correlation with subsequent neoplastic/malignant histologic diagnoses. The MTR sensitivity for malignant disease was 89% and the negative predictive value was 91%.

CONCLUSIONS

MTR analysis reveals the importance of cytologic atypia as a determinant of malignancy risk in AUS cases. Periodic analysis of MTR data alongside individual pathologist AUS rates can help refine diagnostic criteria and potentially reduce AUS overuse.

MSRSGC: A prospective study of heterogenous group atypia of undetermined significance

CONTEXT

: Many standard books, literatures, and internet described the characteristic lineament of each salivary gland lesion. Nevertheless, there are dozens of disarray, confusion, and unmanageable morphological features regarding proper reporting. To fight with these issues, Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) was introduced in 2018, but still the third category, Atypia of undetermined significance (AUS), poses difficulties for the pathologists and clinicians for a definite interpretation.

AIM

: The aim is to analyze the risk of neoplasia (RON) and risk of malignancy (ROM) of Milan's category III (AUS) by subdividing into six groups based on cytolomorphology.

SETTINGS AND DESIGN

:The duration of study was from March 2018 to may 2021 with the focus on ROM and RON of all Milan's categories with especial attention on AUS.

METHODS AND MATERIAL

: Result of total 329 Fine Needle Aspiration Cytology of salivary glands was categorized according to MSRSGC. On the basis of cytomorphology, further subtyping of AUS and its cytohistopathology correlation was done. The ROM and RON of each subtype was analyzed.

STATISTICAL ANALYSIS

All data were calculated by existing formulas.

RESULTS

Out of 329 aspirates, 24 (07.29%) cases belong to AUS with availability of histology in 13 (54.17%) cases. RON and ROM was 84.62% and 53.85%, respectively. Cases of lymphocytes with nuclear atypia (L-NA) was the most prevalent (29.17%). The RON were 60.00%, 68.57,% 84.62%, 94.87%, 87.50%, 100%, 100% and the ROM were 20.00%, 11.42%, 53.85%, 05.13%, 43.75%, 83.33% and 100% in each Milan's categories I, II, III, IVa, IVb, V, and VI, respectively. ROM was the highest in cystic fluid with nuclear atypia (C-NA) (100.0%), followed by basaloid cells (75%), L-NA (66.675), and SC (50%), but ROM was zero in NA and oncocytic cells.

CONCLUSIONS

Subgrouping of AUS helps to dissipate the muddiness and provide more exact and reproducible diagnostic and prognostic tool.

Molecular testing results as a quality metric for evaluating cytopathologists' utilization of the atypia of undetermined significance category for thyroid nodule fine-needle aspirations

INTRODUCTION

The use of the indeterminate category of atypia of undetermined significance (AUS) for thyroid fine-needle aspirations (FNAs) should be kept to a minimum. Here, we investigate the utility of combining AUS utilization rates with Afirma (Veracyte, Inc., South San Francisco, CA) genomic sequencing classifier (GSC) molecular testing results as a quality improvement metric for describing cytopathologist practice patterns.

MATERIALS AND METHODS

Thyroid FNAs evaluated in our laboratory by 9 cytopathologists from December 2017 to July 2021 were stratified by Bethesda diagnostic category, and Afirma GSC testing results for AUS cases were compiled and correlated with AUS call rates.

RESULTS

Over this period, the laboratory AUS rate was 22.3% (672 of 3008), with an individual cytopathologist range of 11.6% to 39.3%. Afirma GSC testing had suspicious (GSC-S) results in 29% (48 of 167) of cases, with a cytopathologist range of 5% to 67%. Linear regression analysis of individual AUS rates versus Afirma GSC-S rates demonstrated no significant relationship between these 2 variables. However, based on the pattern of AUS use and GSC-S rates, a novel conceptual framework for understanding cytopathologist practice patterns is proposed.

CONCLUSIONS

Combining molecular testing results with AUS call rates of thyroid nodules can provide a more nuanced explanation of cytopathologist practice patterns, and can be utilized to provide directed feedback to bring individual cytopathologist diagnostic category use in line with laboratory averages or published benchmarks.

Milan System for Reporting Salivary Gland Cytopathology- An Experience from Western Indian Population

Introduction:

Fine-needle aspiration cytology (FNAC) can be challenging to provide a precise diagnosis in salivary gland cytopathology due to diversity of lesions and cytomorphological convergence between the tumors and within the same tumor of salivary gland. The recently proposed Milan System for Reporting Salivary Gland Cytopathology (MSRSGC) provides a risk stratification-based classification system with an intrinsic risk of malignancy (ROM) for each diagnostic category, which aims to furnish useful information to the clinicians. This study was undertaken to evaluate the diagnostic utility and validity of MSRSGC.

Methods and Material:

In this retrospective study, FNAC done for all salivary gland lesions over a period of two years were retrieved. All cases were categorized according to MSRSGC and correlated with histopathological follow-up, wherever available. ROM was calculated for each category.

Results:

The cases belong to following categories: non-diagnostic (1.27%), non-neoplastic (30.38%), atypia of undetermined significance (5.06%), benign neoplasm (46.84%), salivary gland neoplasm of uncertain malignant potential (1.27%), suspicious for malignancy (1.27%), and malignant (13.92%). Out of 79 cases, 50.63% had follow-up. The ROM were 0% for category II and IVa, 50% for category III, and 100% for category IVb, V, and VI. The sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy were recorded as 77.78%, 100%, 100%, 91.3%, and 93.33%, respectively.

Conclusions:

Application of MSRSGC has immense value for standardization of reporting of salivary gland FNAC. Our data corresponds to the studies done worldwide and recommends the use of MSRSGC for future diagnostic purposes.

Malignancy is associated with microcalcification and higher AP/T ratio in ultrasonography, but not with Hashimoto's thyroiditis in histopathology in patients with thyroid nodules evaluated as Bethesda Category III (AUS/FLUS) in cytology

The predictors of malignancy are important for the decision of appropriate management in nodules with atypia of undetermined significance/follicular lesion of undetermined significance (AUS/FLUS). Our aim was to determine the ultrasonographical, clinical, and biochemical predictors of malignancy in these patients. A total of 427 patients with cytologically Bethesda Category III (AUS/FLUS) thyroid nodules were included in this retrospective study. We divided the nodules into two subgroups according to the histopathology as benign and malignant, and compared the preoperative ultrasonographical, clinical, and biochemical findings. In overall, 427 patients with 449 AUS/FLUS nodules who had undergone surgery, the rate of malignancy was 23.4 % (105/449). When evaluated separately, the rate of malignancy was 25.8 % in nodules with AUS (82/318) and 17.6 % in nodules with FLUS (23/131) (p = 0.061). The vast majority of malignant specimens in histopathology consisted of papillary thyroid carcinoma (PTC) (n = 91, 86.7 %). Preoperative ultrasonographic features of 105 malignant nodules in histopathology were compared with the 344 benign nodules in histopathology. Anteroposterior/Transverse (AP/T) ratio was significantly higher in malignant group compared to benign group (p = 0.013). In multiple logistic analysis, we found that higher AP/T ratio and microcalcification were independently associated with malignancy (p < 0.05). The malignancy-associated cut-off value of AP/T ratio at maximum sensitivity and specificity was ≥0.81. We did not find any correlation between malignancy and Hashimoto's thyroiditis in histopathology in multivariate analysis (p > 0.05). In Bethesda Category III nodules with higher AP/T ratio and microcalcification, surgery might be considered as a first therapeutic option instead of repeat fine-needle aspiration biopsy or observation.