Expression of CD56 and HBME-1 in surgically excised thyroid nodules

Abstract

Introduction: Thyroid nodules represent a wide spectrum of neoplasms with different biological behaviors Majority of thyroid nodules are benign, but malignancy is found in approximately 5–15% of cases. Accurate diagnosis of these thyroid nodules is difficult, because of subtle and subjective histomorphological criteria. Immunohistochemistry method may play a complementary role to clarify diagnostic dilemma. CD56 is a neural cell adhesion molecule expressed on thyroid follicular cells.  Down regulation of CD56 can shows correlation with tumour progression. Hector Battifora mesothelial epitope (HBME-1) is a membranous antigen located on follicular thyroid tumour cells and normal thyroid tissue is negative for HBME-1. Objective: To observe the expression of CD56 and HBME-1 in the diagnosis of surgically excised thyroid nodules. Methods: This cross sectional study was conducted in the Department of Pathology, Chittagong Medical College, Chattogram from March 2019 to February 2021. Immunohistochemistry was done at Armed Forces Institute of Pathology, Dhaka Cantonment. Sixty-three surgically resected thyroid nodules were evaluated to find out their histopathological type. Immunostaining was done by using primary antibody against CD56 (FLEX Monoclonal Mouse Anti-Human CD56 Clone 123C3 Ready to use (LINK). Denmark) and HBME-1 (Anti–Mesothelioma mouse monoclonal antibody HBME-1ab2383. Abcam, UK). Patient’s demographic data were collected and recorded in a predesigned data sheet. Statistical analysis was carried out as required. Ethical practice was ensured in every step of the study. Results: Among the 63 cases, mean age (±SD) of the patients was 39.47 ± 13.67 years and male to female ratio of 1:6.9. Thirty-four patients (76.3%) had multiple nodules. Among the 63 patients, 68.3% (43 cases) were histologically diagnosed as benign and 31 .7% (20 cases) as malignant thyroid nodules according 2017 WHO classification of thyroid tumours. Immunohistochemistry was performed using the markers CD56 and HBME-1 for all the 63cases.In present study weak to strong positive expression of CD56 was observed in 33(76.7%) cases out of 43 benign nodules whereas negative CD56 expression was observed in 20(100%) malignant cases. CD56 expression between benign and malignant lesion was statistically significant (p value, 0.002). HBME-1 was showed positive expression for 17(85%) out of 20 cases of malignant nodules and negative expression was observed in benign nodules. No statistically significant (p>0.250) difference was found between HBME-1 expression and histopathological diagnosis. So this study has improved the better understanding of thyroid nodules by expression of these immunomarkers (CD56 and HBME1) and thus may help the patients for selecting appropriate management protocol. Conclusion: In this study, Positive HBME-1 staining is a strong indicator of malignancy, although negative staining does not rule it out. IHC with CD56 and HBME-1 is considered to be important ancillary test in the diagnosis of thyroid neoplasms, but it does not replace the conventional histopathological examination.