Purpose: The present study aimed to evaluate the diagnostic roles of CD56 immunohistochemistry in differentiating various thyroid lesions.
Methods: A meta-analysis was performed to evaluate the rate of loss of CD56 immunohistochemistry expression from 13 eligible studies regarding various thyroid lesions, including papillary thyroid carcinoma, follicular carcinoma, and follicular adenoma. To confirm the value of CD56 immunohistochemistry in differentiating various thyroid lesions, a diagnostic test accuracy review was conducted.
Results: An 87.8%, 79.1%, 11.9%, 25.5%, and 19.6% loss of CD56 immunohistochemistry expression was identified in papillary thyroid carcinoma, follicular carcinoma, follicular adenoma, benign follicular nodule, and Hashimoto's thyroiditis, respectively. In the normal thyroid tissue, the rate of loss of CD56 expression was 1.6%. Classical, follicular, diffuse sclerosing, tall cell, and encapsulated variants of papillary thyroid carcinoma showed an 88.4%, 75.3%, 97.2%, 91.7%, and 91.7% loss of CD56 expression, respectively. In the comparison between the follicular variant of papillary thyroid carcinoma and follicular adenoma, the pooled sensitivity and specificity of CD56 immunohistochemistry was 0.82 (95% confidence interval (CI) 0.70, 0.90) and 0.94 (95% CI 0.83, 0.99), respectively. The diagnostic odds ratio and the area under curve on summary receiver operating characteristic curve was 51.43 (95% CI 5.83, 453.88) and 0.9387, respectively.
Conclusion: Collectively, these results indicate that the rate of loss of CD56 immunohistochemistry expression was significantly higher in malignant tumors, such as papillary thyroid carcinoma and follicular carcinoma, than in follicular adenoma, benign follicular nodule, and Hashimoto's thyroiditis. As such, CD56 immunohistochemistry can be useful in differentiating follicular variant papillary thyroid carcinoma from follicular adenoma.
Keywords: CD56; Diagnostic test accuracy review; Immunohistochemistry; Meta-analysis; Thyroid.