Value of immunohistochemical expression of p27 and galectin-3 in differentiation between follicular adenoma and follicular carcinoma.

INTRODUCTION: Thyroid neoplasms represent a broad spectrum of tumors with different biologic behaviors. Follicular neoplasms are classified as benign or malignant depending on the presence or absence of capsular and/or vascular invasion; however, evaluation of these features can be challenging on histopathologic examination. Galectin-3 is a member of lectin family and seems to play a significant role in a number of biological processes. p27 is a key regulator of progression from G1 to S phase.
MATERIALS AND METHODS: In this study, we investigated the differential expression of both p27 and galectin-3 in both follicular adenomas and follicular carcinomas. The study was conducted on archival blocks retrieved from the pathology department at National Cancer Institute, Cairo University, diagnosed between 2001 and 2009 and included 22 cases of follicular adenomas, 22 cases of follicular adenomas with atypical features, 13 cases of minimally invasive follicular carcinomas, and 25 cases of widely invasive thyroid carcinomas.
RESULTS: p27 and galectin-3 immunohistochemical results were significantly different between follicular adenomas including those with atypical features and minimally and widely invasive follicular carcinomas with highly statistically significant difference, recording sensitivity of 100%, specificity of 97.4% as regards p27 and sensitivity of 71%, specificity of 86.36% as regards galectin-3.
CONCLUSION: p27 is a reliable marker in distinguishing follicular adenomas including atypical types from follicular carcinoma. Galectin-3 is also a fairly reliable marker in distinguishing follicular adenomas from carcinomas; however, it should be combined with other markers to increase its accuracy. We recommend the use of immunohistochemical panels of markers in follicular patterned thyroid lesions, notably in controversial cases.