Papillary carcinoma of thyroid: A 30-yr clinicopathological review of the histological variants

Many histological variants of PTC have been described and some are known to have prognostic significance. However, their relative frequencies and associated clinicopathological features in a large cohort of patients with PTC treated at a single institution have seldom been documented. We reclassified 1035 malignant thyroid tumors treated in a 30-yr study period, into variants of PTC according to current histological criteria and analyzed their features. Six hundred and fifty two patients (153 men; 499 women) with PTC were identified. PTC accounted for 72.8% of primary thyroid cancers. Conventional papillary carcinoma (n=300) accounted for 46% of PTC and papillary microcarcinoma 27.8% (n=181). The frequencies of the common histological variants were follicular (17.6%, n=115), tall cell (4%, n=26), and diffuse sclerosing (1.8%, n=12). Uncommon histological variants including solid (n=5), diffuse follicular (n=5), papillary carcinoma with focal insular component (n=3), columnar cell (n=2), papillary carcinoma with fasciitis-like stroma (n=2), and oncocytic (n=1) were also noted. Histological variants of PTC had different age presentation, tumor size, frequencies of lymph node metastases, calcification, metaplastic bone, and psammoma bodies, when compared with conventional PTC. We conclude that a high prevalence of different variants of PTC with distinct clinico-pathological features can be documented. Recognition of these histological variants may be important for better management of patients with PTC.