CYTOKERATIN 19 EXPRESSION IN DIAGNOSIS OF PAPILLARY THYROID CARCINOMAS

Abstract

Papillary thyroid carcinoma (PTC) is the most common form of malignant thyroid neoplasm. Despite the propensity for lymphatic dissemination to
cervical nodes, the majority of them have an excellent long term prognosis, hence accurate diagnosis plays a key role.1 Diagnostic dilemma may
arise when an encapsulated nodule with a follicular pattern of growth exhibits clear nuclei with grooves or darkly staining colloid and
distinguishing follicular adenoma (FA) from encapsulated follicular variant of papillary thyroid carcinoma (FVPTC) becomes difcult.2The
distinction between these lesions is important because prognosis and management differ. Multinodular goitre (MNG) with delicate papillary
budding and focal nuclear clearing may be confused with PTC.3The use of monoclonal antibodies for immunohistochemistry can improve
diagnostic accuracy when combined with standard morphologic criteria. PTC have been shown to express CK19 with strong diffuse cytoplasmic
reactivity. SUMMARY: CK19 expression is helpful in diagnosing PTCs where there are diagnostic dilemmas morphologically.