Objectives: Follicular thyroid lesions represent a heterogeneous group with variable biological behavior. Discrimination between benign and malignant follicular thyroid lesions by histologic examination poses a significant challenge to pathologists. Recently, CD56 has attracted attention as a potential diagnostic marker in follicular thyroid lesions.
Materials and Methods: A retrospective immunohistochemical and statistical analyses of CD56 expression in 68 cases of follicular thyroid lesions were done.
Results: CD56 expression was significantly higher in papillary thyroid carcinoma (PTC) (conventional and follicular variants) compared to other categories of follicular thyroid lesions, and it was significantly higher in the follicular variant of papillary carcinoma compared to follicular adenomas (FA) and hyperplastic nodules (HN). A bivariate analysis showed that the malignancy in follicular thyroid lesions was significantly associated with higher CD56 expression and older patientsí age. Both parameters were used to build a logistic regression model and equation for prediction of malignancy in follicular thyroid lesions. On the application of the equation to the studied cases, it was found to conform to their diagnostic nature.
Conclusions: We conclude that CD56 could serve as a good positive marker favoring the diagnosis of PTC (conventional and follicular variants) over other categories
of follicular thyroid lesions. It also could be of value in differentiating follicular variant of papillary carcinoma from other lesions of benign nature such as FA and HN. CD56 expression is significantly associated with malignant behavior in thyroid follicular lesions, which suggests a role for CD56 in tumorogenesis. More importantly, the developed model and equation based on CD56 expression and patient's age might be of value in the prediction of malignancy in follicular thyroid lesions, but it needs to be validated on a large scale accompanied by follow-up.
CD56, follicular thyroid lesions, logistic regression model, prediction of malignancy