Validation of CK-19 and HBME-1 Expression Pattern in FNACs to Supplement Morphological Evaluation for Preoperative Diagnosis of Thyroid Lesions

Aim: Fine Needle Aspiration Cytology is the cost effective, quick and minimally invasive method for the initial evaluation of thyroid nodule. But it poses a diagnostic challenge in differentiating benign follicular adenoma from follicular carcinoma and follicular variant of papillary carcinoma as they have similar cytological appearance. Present study focused on the identification of a biological marker for the differential diagnosis of thyroid malignancy in indeterminate cases.

Place and Duration of the Study: Division of cancer Research, Regional Cancer Centre, Kerala, India, between August 2009 to September 2014.

Methodology: Immunohistochemistry was performed using Ret (Rearranged during transfection), Hector Battifora Mesothelial Cell Antigen-1 (HBME-1), Cytokeratin-19 (CK-19), Keratan sulphate (KS), Thyroid peroxidase (TPO), Estrogen receptor (ER) and Progesterone receptor (PR) on cell block prepared from FNA material and corresponding tissue sections on 153 samples. Western blot analysis of ER and PR was performed in surgically excised fresh tissue specimens.

Results: The present study found that HBME-1 is highly significant (P < .001) for the differential diagnosis with a diagnostic accuracy of 95.96%. Ret immunostaining may serve as good indicator of PTC whereas its sensitivity is very low in other lesions. The diagnostic accuracy of CK-19 was 90.91%. Intense positive staining of TPO was noted in majority of follicular epithelial cells of benign lesions (42.42%). Females had an increased prevalence in our study population so we examined the estrogen and progesterone receptors status in thyroid lesions. The specificity of KS, ER and PR are very low for the differentiation of adenoma from carcinomas of the thyroid.

Conclusion: Present study found that the combination of two markers may give a more accurate way in the differentiation of thyroid nodules in problematic cases. So we suggest morphological evaluation along with immunocytochemistry of HBME-1 and CK19 can help the differential diagnosis of thyroid lesions in FNAs.