The Interobserver Reproducibility of Thyroid Fine-Needle Aspiration Using the UK Royal College of Pathologists’ Classification System

Abstract

The overall interobserver reproducibility of thyroid fine-needle aspiration (FNA) has not been comprehensively assessed. A blinded 6-rater interobserver reproducibility study was conducted of 200 thyroid FNA cases using the UK System, which is similar to The Bethesda System for Reporting Thyroid Cytology: Thy1, nondiagnostic; Thy2, nonneoplastic; Thy3a, atypia, probably benign; Thy3f, follicular lesion; Thy4, suspicious of malignancy; and Thy5, malignant. There was good interobserver agreement for the Thy1 (κ = 0.69) and Thy5 (κ = 0.61), moderate agreement for Thy2 (κ = 0.55) and Thy3f (κ = 0.51), and poor agreement for Thy3a (κ = 0.11) and Thy4 (κ = 0.17) categories. Combining categories implying surgical management (Thy3f, Thy4, and Thy5) achieved good agreement (κ = 0.72), as did combining categories implying medical management (Thy1, Thy2, and Thy3a; κ = 0.72). The UK thyroid FNA terminology is a reproducible and clinically relevant system for thyroid FNA reporting. This study demonstrates that international efforts to harmonize and refine thyroid cytology classification systems can improve consistency in the clinical management of thyroid nodules.

Introducing the reporting system for thyroid fine-needle aspiration cytology according to the new guidelines of the Japan Thyroid Association [Review]

“…The same diagnostic system was also proposed as Thy3a in the recent UK Royal College of Pathologists' classification (UK system) [17,18,20,53,54]. The probability of malignancy (PTC type) was as high as 40-60% in indeterminate B, which may be exactly the same category as Thy3a in the UK system, and different from the AUS in the Bethesda system of the low-risk (5-15%) category [11,17,18,20,26,53,54,60]. Indeterminate B of the JTA system could be divided into two categories: AUS and suspicious for borderline and favor malignant (Table 1).…”

“…3). Some researchers emphasized that PTC-type nuclear features in cytology were not associated with a low risk [4, [17][18][19][20] …”

Thyroid Nodules with Atypia or Follicular Lesions of Undetermined Significance (AUS/FLUS): Analysis of Variables Associated with Outcome

“…FNA is used for estimating malignancy risk of the nodule to decide whether patient is a candidate for surgery or not (Cibas and Ali, 2009). Therefore, malignancy risk of each cytopathology result has been determined by different organizations to recommend best treatment options for each category (Cibas and Ali, 2009;Gharib et al, 2010;Kocjan et al, 2011). Additionally, these categorizations aim to decrease the rate of indeterminate results and provide a common language in between different disciplines, such as pathology, endocrinology and surgery.…”

“…These types of nodules are also defined as Thy3a category defined by The Royal College of Pathologists (TRCP) and as Class 3 (with suspicious follicular lesions also included) by the American Association of Clinical Endocrinologists/ Associazione Medici Endocrinologi/European Thyroid Association (AACE/AME/ETA) Task Force. Both guidelines recommend surgery to exclude malignancy unless the clinical, ultrasonographic, cytological and immunocytochemical features are considered favorable (Gharib et al, 2010;Kocjan et al, 2011).…”

Retrospective cytological evaluation of indeterminate thyroid nodules according to the British Thyroid Association 2014 classification and comparison of clinical evaluation and outcomes

“…Some studies have considered the absence of suspicious US findings on follow-up to be an indicator of benignity, which may also explain the differences in percentages (Ho et al, 2014;Rosario, 2014;Yoo et al, 2015). Finally, some authors have reported a very poor inter-observer reproducibility for the Thy 3 category, in contrast to the good agreement seen for the other BTA categories (Kocjan et al, 2011).…”