[389] Comparison between the Bethesda and the British Thyroid Association-Royal College of Physicians Systems for Reporting Thyroid Cytopathology: Experience in Two Hospitals

M Bongiovanni, WC Faquin, S Crippa. Geneva University Hospitals, Geneva, Switzerland; Harvard Medical School, Boston; Institute of Pathology, Locarno, Switzerland

Background: Thyroid FNA has proven to be one of the most effective tools for guiding the initial management of patients with thyroid nodules. The new 6-tiered Bethesda System for Thyroid FNAs sponsored by the National Cancer Institute and the 5-tiered British Thyroid Association - Royal College of Physicians thyroid FNA System offer two approaches to the problem of reporting thyroid FNA results. The efficiency of these 2 systems has particular significance for the European cytology community. In this study, we present the combined experience from our institutions for reporting thyroid FNAs using these two different systems and evaluate their efficacy based upon surgical follow up.
Design: Data on thyroid FNAs and their corresponding surgical specimens were collected at our two institutions over a two-year period. We compared the sensitivity and specificity for each of the component groups within the 2 systems where a diagnosis lead to surgery (CAT 3, 4, 5, 6 and THY 3, 4, 5 versus benign).
Results:

Table 1
Bethesda systemBritish system
Patients210289
Nodules294386
Age (range)51 (7-88)50 (16-86)
Sex (F/M)178/32234/55




Table 2
Bethesda systemFNA (%)Positive histologyNegative histologyBritish systemFNA (%)Positive histologyNegative histology
CAT20 (28%)51 (72%)THY26 (37%)44 (63%)
131 (10.5)04134 (8.8)24
2156 (53)2152306 (79.3)224
34 (1.4)//
479 (27)528324 (6.2)314
513 (4.4)4446 (1.6)51
611 (3.7)90516 (4.1)14
§1 benign nodule in Hashimoto thyroiditis

The sensitivity for CAT 3, 4, 5, 6 and for THY 3, 4, 5 were almost equal in the two reporting systems, Bethesda and British, (90% vs 91.6%), while specificity was higher in the British (31.9% vs 60%). Interestingly, the number of cases in the CAT 4 and THY 3 categories (suspicious/indeterminate) differed significantly between the two reporting systems (27% and 6.2%). For these two categories, the rate of malignancy on surgical excision is similar (18% and 21%), with a PPV of 15% and 17% respectively.
Conclusions: The two reporting systems, the Bethesda and the British, show similar sensitivities but the British system exhibited better specificity, possibly related to differences in the use of the so called “grey zone” (CAT 4 and THY 3) categories. Larger studies will be useful to further confirm these data.
Category: Cytopathology

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 95, Tuesday Morning

 

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