Improved preoperative definitive diagnosis of papillary thyroid carcinoma in FNAs prepared with both ThinPrep and conventional smears compared with FNAs prepared with ThinPrep alone

Abstract

ThinPrep (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. 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. 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). 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.