Ultrasound-guided fine-needle aspiration of the thyroid assessed by Ultrafast Papanicolaou stain: data from 1135 biopsies with a two- to six-year follow-up.

One of the limitations of fine-needle aspiration (FNA) of the thyroid is difficulty in distinguishing the follicular variant (FV) of papillary thyroid carcinomas (PTC) from follicular neoplasms. By highlighting the "Orphan Annie-eyed" clear nuclei of the former, the Ultrafast Papanicolaou stain (UFP) easily separates these two entities. One thousand one hundred thirty-five ultrasound-guided FNAs of the thyroid were assessed by UFP with immediate biopsy results reported to the patients in a busy radiology office in Manhattan from November 1994 to December 1998. Of the 77 thyroid cancers resected, 22 were FVPTC and 17 were microcarcinomas (1 medullary carcinoma, 16 PTC). The rates of "unsatisfactory," "cancer," "suspicious for cancer," "follicular neoplasm," and "benign" cytology were 0.7%, 4.4%, 2.6%, 10.2%, and 82.1%, respectively and the cancer yields at surgery were 98%, 81.8%, 15.8%, and 0% respectively. Of the 1127 satisfactory FNAs in the series with a 2- to -6 years of clinical follow-up, a false-negative rate of 0% and a false-positive rate of 1.5% were obtained. Of the 169 surgical follow-ups with satisfactory FNAs, a sensitivity of 100%, specificity of 66.7%, positive predictive value of 87.4%, negative predictive value of 100%, and global accuracy of 89.9% were achieved. The paradoxical combination of low unsatisfactory rate and low false-negative rate is attributed to (1) the use of needle puncture without syringe to obtain enough microfollicles from the exceedingly bloody aspirates from follicular neoplasms for a diagnosis, (2) eliciting history of neck trauma to confirm hematomas, (3) using UFP to highlight the grape-like watery clear nuclei of FVPTC evident with a 4x objective, and (4) the precise guidance by ultrasound in sampling microcarcinomas.