The role of galectin-3, CD44v6 and thyroid peroxidase expression in differantial diagnosis of thyroid follicular neoplasms

SUMMARYFollicular patterned lesions of thyroid encompassing 4 entities - follicularadenoma (FA), follicular carcinoma (FC), papillary carcinoma follicular variant (PCFV)and nodules of goiters (adenomatoid nodüles, AN)- represents a major diagnosticdilemma. In present study we aimed to assess the role of 3 promissing markers -galectin 3 (gal-3), CD44v6, thyroid peroxidase (TPO)-in distinguishing benign frommalignant follicular lesions.One hundred and four cases were evaluated according to WHO 2004classification (14 AN, 36 FA, 29 FC, 24 FVPC, 1 well differentiated carcinoma,NOS).Immunohistochemical evaluation revealed cytoplasmic positivity with gal-3 and TPO,and membranous and/or cytoplasmic stainings with CD44v6.For gal-3, sensitivity, specivity and diagnostic accuracy were 59.25%, 84%and 71.15% respectively. Although the negativity can not exclude malignancy,positivity can be thought as a sign of malignant feature or potential for the lesions ofwhich there is strong suspect of malignancy. Integration of gal-3 immunoreactivitywith both clinical and histological findings represents a reliable approach to thethyroid neoplasm.For TPO, less than 80% staining was accepted as a sign of malignancy. Inthat case sensitivity, specivity and diagnostic accuracy were 61%, 70% and 65.4%respectively. We observed decreased expression in oncocytic variant of FA. Thus thespecivity decreases to 30.55% for distinguishing FA from malignant follicular lesions.TPO is not a reliable marker in differantial diagnosis of benign and malignant follicularlesions when it is used alone. In case of a cilinical or histological suspect itsdecreased expression can be used as a malignancy marker together with gal-3positivity.Sensitivity and diagnostic accuracy of CD44v6 was 20.4% and 52.9%respectively. It does not seem to be reliable in distinguishing benign/malign follicularthyroid lesions.