The impact of the Bethesda System for Reporting Thyroid Cytopathology (TBSRTC): A retrospective study of 828 aspirates with emphasis on the prior ""indeterminate"" category

Abstract

Objective: We evaluated the impact of implementing TBSRTC in an academic community hospital. Method: FNAs from Jan/2004 to Dec/2010 were reclassified in TBSRTC: nondiagnostic (ND), benign (B), atypia or follicular lesion of undetermined significance (AUS/FLUS), suspicious for follicular neoplasm (FN), suspicious for malignancy (S) and malignant (M). FLUS and FN were classified according to presence of Hürthle cells as HCLUS and FN-HC. Results: A total of 828 FNAs (480 patients) were obtained: 46 ND (5.55 %), 682 B (82.4 %), 9 S (1.1 %) and 25 M (3.0 %). The 66 (8.0 %) indeterminate categories were reclassified: 1 ND (1.5 %), 8 B (12.1 %), 5 AUS (7.6 %), 34 FLUS (51.5 %), 5 HCLUS (7.6 %), 3 FN (4.5 %), 9 FN-HC (13.6 %) and 1 S (1.5 %). Thyroidectomies were performed in 125 patients (26 %): benign lesions in 83 (66.4 %), 7 (5.6 %) follicular adenoma and 2 (1.6 %) follicular carcinomas, 1 (0.8 %) medullary carcinoma, 21 (16.8 %) papillary carcinomas and 16 (12.8 %) papillary microcarcinomas (PMC). Risk of malignancy (RM) excluding PMC: B 1.4 %, AUS/FLUS/HCLUS 5 %, FN/FN-HC 11.1 %, SM 50 % and M 77.8 %. Conclusion: TBSRTC criteria led to more specific diagnosis. FN/FN-HC category has a two-fold RM when compared to AUS/FLUS/HCLUS.