BACKGROUND: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.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. © 2010 American Cancer Society.

Objective: To determine whether or not significant differences in the risk of malignancy exist between subgroups of atypical follicular cells in The Bethesda System for Reporting Thyroid Cytology (TBSRTC) in patients who underwent surgical resection. Study Design: Between 2004 and 2009, consecutive thyroid fine-needle aspirates at our institutions with a cytologic diagnosis of ‘atypical follicular cells’ were retrieved and subclassified using the diagnosis and diagnostic comment as: (1) atypical follicular cells with equivocal features of papillary carcinoma [cannot exclude papillary thyroid carcinoma (PTC)] and (2) atypical follicular cells, other patterns. The risks of malignancy for excised nodules were calculated and comparisons were made between these subgroups. Categorical analysis was performed using a 2-tailed Fisher’s exact test, and p < 0.05 was considered statistically significant. Results: A total of 7,072 thyroid fine-needle aspiration cases were retrieved, with 1,542 (21.8%) having a histologic follow-up. There were 222 (3.1%) cases of ‘atypical follicular cells’, with 127 (57.2%) having a histologic correlation and 33 having confirmed malignancies. Atypical follicular cells, cannot exclude PTC, have a significantly higher risk of malignancy than atypical follicular cells, other patterns (45.8 vs. 13.9%, p < 0.01). Conclusions: Atypical follicular cells with equivocal features of papillary carcinoma is not a low-risk cytologic diagnosis.