Papillary thyroid carcinoma with different histological patterns.

Tumor-node-metastasis (TNM) staging is the most commonly used model for evaluating therapeutic strategies for papillary thyroid cancer (PTC). Additionally, different histopathological patterns and variants of PTC have been reported to influence the prognosis of these patients. We reviewed the clinical presentation, cancer recurrence, and cancer-specific mortality of the most frequent histological patterns, including the follicular variant (FVPTC), insular pattern, tall cell pattern, diffuse sclerosing type, PTC with Hashimoto's thyroiditis, and multicentric PTC. The tall cell variant of PTC is a more aggressive variant than classical PTC and has a poor prognosis. The high expression of Muc 1 and type IV collagenase in these tumors may facilitate stromal degradation and increase the invasive potential. In contrast, approximately 18% of PTC patients have been identified as having FVPTC. FVPTC patients have a better survival rate than those with follicular thyroid cancer, and fewer instances of lymph node or soft tissue invasion than control patients with classical PTC. The diffuse sclerosing variant of PTC predominantly observed in young patients is a rare aggressive tumor that requires intensive treatment. Despite characteristic clinical and histological features that facilitate easy diagnosis, pre-operative fine needle aspiration cytological diagnosis of this variant is often challenging. Different histological variants of PTC with other histological patterns are important for predicting cancer recurrence. In addition to TNM staging, high-risk histological patterns of PTC require more aggressive follow-up examinations and postoperative adjuvant therapies.