Fine-needle aspiration (FNA) is widely accepted as the initial test to evaluate thyroid nodules; however, inadequate and suboptimal specimens have been 1 of its limitations. Unsatisfactory rates of 4.1% to 43% have been reported, but suboptimal specimens with adequate epithelial cells and other limiting factors, such as clotting, often are not addressed. The authors' institution has a low unsatisfactory rate, especially for thyroid biopsies performed under ultrasound in the Interventional Radiology (IR) Department. In addition to on-site evaluation for all cases, they concomitantly use thin, 22/20-gauge core needle biopsy (CB) crush preparations (CP) for unsatisfactory/suboptimal FNAs. The CB usually is done after 2 FNA passes and, in most cases, is exhausted by making an air-dried CP, which is evaluated on site for adequacy; any residual tissue is processed for tissue sections. Experience is required to interpret CP on air-dried smears. In this report, the authors describe a complementary approach to thyroid biopsy that has worked well.
All thyroid FNA and CB/CP that were performed in the IR Department during the year 2005 were reviewed. Follow-up histology and records of all procedural complications were retrieved.
Seven hundred thirteen thyroid biopsies qualified, 225 biopsies (31%) had FNA with CB/CP (85% had only CP for evaluation), and 488 biopsies (69%) had only FNA. The final unsatisfactory rate in IR for FNA was 8.7%; this was reduced to 3.4% with the use of CB/CP. The addition of CB also helped to obtain a more definitive diagnosis in suboptimal FNA specimens. Cytologic-histologic correlation was comparable for FNA only cases and FNA/CB cases. There were no significant procedural complications in CB cases.
FNA in conjunction with a thin CB/CP performed during the same procedure is a safe technique that can reduce the rate of unsatisfactory and suboptimal thyroid biopsy.