Expression of human telomerase reverse transcriptase (hTERT) in thyroid neoplasms.

PURPOSE: Distinction of thyroid neoplasms that include papillary carcinoma (PC) and follicular carcinoma (FC) from benign thyroid neoplasms can be performed successfully by histopathologic examination in most of the cases. However, in some cases it may be difficult to distinct PC and FC as well as FC and follicular adenoma (FA) and also FA and the dominant nodule of multinodular goiter (MNG) histopathologically. In this study, we aimed to determine the role of expression of the human telomerase reverse transcriptase (hTERT) in the distinction of thyroid neoplasms and its relation with prognostic factors by immunohistochemical methods.

METHODS: This retrospective study included 138 cases histopathologically diagnosed with benign and malignant thyroid neoplasia. Sections obtained from formalin-fixed paraffin- embedded blocks were stained with hTERT antibody. Cases were divided into hTERT-positive and -negative categories according to hTERT expression score that included percentage and intensity of staining in neoplastic cells.

RESULTS: hTERT expression was negative in 93 (67.4%) and positive in 45 (32.6%) patients. Twenty-three (46.0%) of 50 PC, 12 (36.0%) of 33 FA, 1 (10.0%) of 10 FC, 4 (13.0%) of 31 MNG, 2 (66.0%) of 3 medullary carcinoma (MC) patients were found hTERT (+), showing that the difference between PC and FC was significant (p=0.034). There was also a significant difference between FA and MNG (p=0.030). There was no difference between FA and FC (p=0.117).

CONCLUSION: The high expression of hTERT can be useful for making a differential diagnosis between PC and FC, and between FA and MNG when histopathological findings are equivocal.