Tall cell variant of papillary thyroid carcinoma: current evidence on clinicopathologic features and molecular biology.

Tall cell variant (TCV) of papillary thyroid carcinoma (PTC) has been recognized for the past few decades as an entity showing aggressive biological behavior; however, there is considerable controversy regarding the definition, clinical and pathological features of TCV because of its rarity and difficult diagnosis. No clinical features can accurately diagnose TCV. Thus, the results of histocytology, immunohistochemistry and molecular genetics tests have important clinical implications for diagnosis. Given the aggressiveness and the increased recurrence and poor survival rates, more aggressive treatment approach and rigorous follow-up is required for patients with TCV. In the present article, we undertook a comprehensive review to summarize and discuss the various aspects of this variant, from morphology to immunohistochemistry, and molecular abnormalities from a practical and daily practice-oriented point of view.