Diagnostic Utility of Immunohistochemistry Markers Galectin-3, CK19 and CD56 in Thyroid Neoplasms: A Descriptive Study

Introduction: The spectrum of follicular patterned thyroid lesions vary from benign to malignant, their categorisation based solely on morphology can often be equivocal. Diagnostic value of immunohistochemistry as a useful ancillary technique is researched in detail, but there is no consensus for use of a marker of diagnostic utility in differentiated thyroid carcinoma. Aim: To evaluate the differential immunohistochemical expression of galectin-3, CK19 and CD56 in benign and malignant thyroid neoplasms. Materials and Methods: The present descriptive cross-sectional study was carried out in the Department of Pathology of a tertiary care centre, Government Medical College, Ernakulam, Kerala, India, from January 2018 to January 2019. Immunohistochemistry staining of galectin-3, Cytokeratin 19 (CK19) and Cluster Differentiation 56 (CD56) was done in 47 thyroid neoplasms. Cytoplasmic and nuclear staining of galectin-3, cytoplasmic or membranous staining of CK19 and loss of membranous expression of CD56 in more than 10% neoplastic cells were taken as positive expression. The data was analysed using IBM Statistical Package for the Social Sciences (SPSS) software version 22.0. Diagnostic test evaluation for markers done by calculating sensitivity and specificity. Results: Out of total 47 neoplasms, 26 were malignant and 21 were benign neoplasms. Of these, galectin-3 positivity was seen in 22 (84.61%) malignant neoplasms and in 2 (9.52%) benign neoplasms. Cytokeratin 19 positivity was seen in 26 (100%) malignant neoplasms and in 7 (33.33%) benign neoplasms. Loss of CD56 expression was observed in 24 (92.3%) malignant neoplasms and in 4 (19.04%) benign neoplasms. Considering histopathology as the gold standard, the sensitivity for detecting malignancy for the 3 markers, galectin-3, CK19 and CD56 was 84.62%, 100%, 92.3% and specificity was 90.48%, 66.67%, 80.95%, respectively. The diagnostic accuracy of galectin-3, CK19 and CD56 was 92.3%, 80.95%, 87.23%, respectively. Diagnostic Odd's ratio for Galectin-3 was 2.3% in the present study. Conclusion: Galectin-3 was found to be a reliable marker for thyroid papillary carcinoma and for differentiating malignancy. The panel consisting of galectin-3 and CD56, is valuable and complementary when used in two marker combination. CK19 was found to be the least specific diagnostic marker of thyroid malignancy.