Human telomerase reverse transcriptase expression in Diff-Quik-srained FNAsamples from thyroid nodules

Fine-needle aspiration (FNA) is a highly sensitive method in the differenti al diagnosis of thyroid nodules. However, 10% of thyroid FNAs are indetermi nate for cancer, and thus additional markers may be useful diagnostically. The authors have demonstrated previously that human telomerase reverse tran scriptase (hTERT) gene expression is useful in the distinction of benign le sions from malignant lesions. They therefore wondered whether the detection of hTERT gene expression was feasible using archival slides. To establish an experimental system, ribonucleic acid was extracted from human anaplasti c thyroid carcinoma cell line (ARO) in cytologic specimens, and reverse tra nscription-polymerase chain reaction (RT-PCR) for hTERT expression was perf ormed. RT-PCR analysis for hTERT gene detection was then performed using 58 Diff-Quik-stained archival FNA samples collected retrospectively. RT-PCR f or human thyroglobulin (hTg) or B-actin gene expression served as a positiv e control. Successful PCR results were obtained from 48 of the 58 cases. Al l 10 slides in which no RT-PCR products were noted were older than 3 years. hTERT gene expression was demonstrated in FNAs from two of seven cases (29 %) of hyperplastic nodule, one of one case (100%) of Hashimoto's thyroiditi s, three of eight cases (38%) of follicular adenoma, three of eight cases ( 38%) of Hurthle cell adenoma, three of four cases (75%) of follicular carci noma, two of two cases (100%) of Hurthle cell carcinoma, and 11 of 18 cases (61%) of papillary carcinoma. All but one of the available 33 correspondin g frozen samples exhibited the same RT-PCR results. This study demonstrates that Diff-Quik-stained thyroid FNA specimens less than 3 years old can be used for the detection of hTERT gene expression by RT-PCR. This test, along with careful cytopathologic examination, may improve our ability to differ entiate benign lesions from malignant lesions in indeterminate FNA samples from thyroid nodules.