Fine-needle aspiration cytology (FNAC) of thyroid nodules is an excellent diagnostic test to distinguish between malignant and benign nodules. However no experienced cytologist can make a diagnosis based on insufficient materials. We examined the ratio and characteristics of cases in which insufficient materials are obtained.
We performed FNAC on 588 patients with thyroid nodules in our hospital from February 2006 to June 2007. In 107 (18.2%), insufficient materials were obtained.
We failed to obtain sufficient materials in 31 (35.2%) of 88 nodules of less than 10 mm in diameter, and in 76 (15.2%) of 500 nodules of more than 10 mm in diameter. In addition, we were unable to obtain sufficient materials in 64 (27.2%) of 235 nodules located under the surface of the trachea, whereas this was the case in 43 (12.2%) of 353 nodules located over it.
The smaller the size of a nodule and the deeper its location, the more frequently insufficient materials are obtained.
