BRAF GENE MUTATION AND CD56 IMMUNOEXPRESSION IN PAPILLARY THYROID CARCINOMA IN DUHOK-IRAQ

Abstract

Background 
 As much as the distinction of papillary carcinoma versus endocrine thyroid lesions may result in some relevant pitfalls, different immunohistochemical panels have addressed this task. The concept of CD56 deletion has been accepted to be specific for papillary carcinoma. 
 Objectives 
 This study was an attempt to test CD56 immunoexpression in papillary carcinoma in this locality and to study the relative association of CD56 immunoexpression with BRAFV600 gene mutation on papillary carcinoma.
 Methods 
 Paraffin embedded, thyroid biopsy specimens containing papillary carcinoma were available for 70 patients. The immunohistochemical technique applied was streptavidin-biotin, using CD56 mouse monoclonal antibodies manufactured by Ventana Corporation (Ventana, Rocklin, Calif). BRAFV600 gene mutation was tested on 48 cases using Real-Time PCR, the target (BRAFV600) DNA was amplified with the mutation-specific primers. 
 Results 
 Out of 70 papillary carcinoma cases, 7.1% showed CD56 immunopositivity and out of 48 cases, 27.1% were positive for BRAFV600 gene mutation. Morphologically, the five CD56 positive cases included 2 follicular variants, 2 anaplastic and 1 conventional papillary carcinoma. On the other hand, the thirteen BRAFV600 positive cases encompassed 8 conventional, 2 microcarcinoma, 2 columnar variant and 1 anaplastic thyroid carcinoma. The frequency of BRAF mutation was statistically highest among the conventional papillary carcinoma. No any association was detected between CD56 immunostaining and BRAFV600 gene mutations.
 Conclusions
 Our findings suggest that although CD56 negativity helps but can not role out papillary thyroid canrcer. There is no any association between CD56 expression and BRAF gene mutation at least among our cases.