Clinical Differences between Classic Papillary Thyroid Carcinoma and Variants

Background: The outcomes of papillary thyroid carcinoma (PTC) variants have been described in a limited number of studies. The purpose of this study was to compare patient outcomes of PTC variants with those of patients with classic PTC. Methods: A single-institution retrospective analysis was performed to review 2,366 patients with classic PTC and 159 patients with PTC variants diagnosed between 1994 and 2004. PTC variant patients were divided into two groups, favorable (n = 119, 119 follicular variants including 14 encapsulated follicular variants) and aggressive (n = 40, including 13 diffuse sclerosing, 11 tall cell, six solid, six oncocytic, and four columnar cell variants). Results: Compared with classic PTC, the favorable and aggressive variants had a significantly larger tumor size (P < 0.001). The favorable variants had significantly lower rates of bilaterality, multifocality, extrathyroidal invasion, cervical lymph node metastasis, stage III and IV disease, and greater male to female ratio (P < 0.05). In particular, the encapsulated follicular variant showed no bilaterality, multifocality, extrathyroidal invasion, lymph node metastasis, and distant metastasis. However, the disease-specific survival and recurrence-free survival of patients with favorable PTC were not different from the patients with classic PTC. The aggressive variants had significantly higher rates of bilaterality and cervical lymph node metastasis compared to the classic PTC (P < 0.05). They had significantly reduced disease-specific survival and recurrence-free survival rates (P < 0.01). Conclusions: Knowledge of the nature of PTC variants, especially aggressive types, is important in predicting patient outcome and providing appropriate treatment. Further study is needed to better understand PTC variants. (J Korean Endocr Soc 24:165~173, 2009) ꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏꠏ