Usefulness of CD56, BRAF and CD15 in the differential diagnosis of thyroid lesions with nuclear features of papillary carcinoma.

INTRODUCTION

Differential diagnosis of thyroid lesions with papillary carcinoma-like nuclear features includes low-risk entities, such as follicular thyroid neoplasia with papillary-like nuclear features (NIFTP), and high-risk entities, such as the tall cell subtype of papillary thyroid carcinoma (TCS). Morphological criteria are essential to distinguish them, but having immunohistochemical techniques to discriminate between these entities would be desirable.

MATERIALS AND

METHODS

8 TCS, 27 papillary carcinomas of classic subtype (CS) and 20 NIFTP were selected. Immunohistochemical staining for BRAF, CD56, B-Catenin, CD15, Muc-1 and Napsin A was performed for each case and correlated with the histological diagnosis.

RESULTS

All TCS cases were positive for BRAF and CD15 (p < 0.05 compared to CS) and none showed positivity for CD56. In the comparison of papillary carcinoma (TCS and CS) and NIFTP, immunostaining for BRAF, CD56 and CD15 showed statistically significant differences.

CONCLUSIONS

BRAF, CD56 and CD15 immunostaining are useful to differentiate between NIFTP, CS and TCS, making it possible to identify a group of tumours with the combination CD56 negative, BRAF positive and CD15 positive that includes 100 % of TCS and 35 % of CS and a group of CD56 positive, BRAF negative and CD15 negative tumours that includes 52 % of NIFTP and 7 % of CS, facilitating the diagnosis.