Variants of Papillary Thyroid Carcinoma

―Cytological features and diagnostic significance―

Abstract

As papillary thyroid carcinoma (PTC) has many characteristic cytological features, the diagnostic accuracy of cytology is extremely high. However, it is not easy to diagnose variants of PTC. This review describes the definitions, clinical features, cytological findings and differential diagnoses of variants of PTC. The significance of diagnosing variants of PTC by cytology is as follows : 1) Diagnosis of variants with an aggressive nature or carrying a poor prognosis is useful for determining the treatment policy and predicting the prognosis ; 2) Diagnosis of the cribriform variant facilitates determination of the surgical procedure ; 3) Familiarity with the cytological findings of the variants would enable easy differential diagnosis. When PTCs with unusual cytological findings are encountered, it is important to consider the possibility of variants.