Improved Preoperative Definitive Diagnosis of Papillary Thyroid Carcinoma in FNAs Prepared With Both ThinPrep and Conventional Smears Compared With FNAs Prepared With ThinPrep Alone

BACKGROUND: Thin Prep (TP) liquid-based preparations are increasingly being used in nongynecologic specimens. Few studies have evaluated TP as a sole diagnostic modality in the setting of thyroid fine-needle aspiration (T-FNA). Herein, the authors evaluate the usefulness of TP as a sole diagnostic modality in a nonsplit sample. METHODS: Consecutive T-FNAs were identified at 2 tertiary care institutions; 1 institution processed thyroid FNA entirely with TP, and the other used a combination of TP and conventional preparations (CP). Cytodiagnoses, surgical pathology, and/or clinical follow-up were recorded. Performance parameters for the 2 settings were compared. RESULTS: A cytologic diagnosis of positive for malignancy was correct in 98.8% of TP+CP cases and in 100% of TP cases. Papillary thyroid carcinoma cases were definitively diagnosed in 53.1% of T-FNAs prepared by TP+CP compared with 34.4% of T-FNAs prepared with TP alone (P=.0015 by Fisher 2-tailed exact test). Of patients ultimately diagnosed with papillary thyroid carcinoma, 89% were initially treated by total thyroidectomy in the TP+CP group compared with 79.5% in the TP-only group (P=.027 by Fisher exact test). CONCLUSIONS: TP as a sole preparatory technique does not improve the usefulness of T-FNA as a screening test. However, combining CP and TP increases the rate of definitive cytologic diagnosis of malignancy in papillary thyroid carcinoma. Thus, combining TP and CP enhances the diagnostic component of T-FNA. Cancer (Cancer Cytopathol) 2011;119:68-73. (C) 2010 American Cancer Society.