Relationship between genetic alterations and clinicopathological characteristics of papillary thyroid carcinoma.

Papillary thyroid carcinoma (PTC) is characterized by proliferation of follicular cells with distinctive nuclear features such as ground glass appearance, nuclear groove and pseudoinclusion. From the proliferation pattern, PTC is divided into several histological subtypes; conventional histology is classified as papillary type, and there are also follicular and solid variants. PTC is heterogeneous in genetic alterations. PTC with BRAF mutation presents a histology of conventional PTC, and follows an aggressive clinical course. Most cases of PTC with RAS mutation show a follicular variant, and prognosis is favorable. RET/PTC1 is observed sporadically and in young cases, and prognosis is favorable. RET/PTC3 is associated with radiation exposure, and the solid variant is frequent. ETV6-NTRK3 may be associated with radiation exposure, and the clinical course is aggressive. Mutation in the telomerase reverse transcriptase promoter is observed in PTC cases involving elderly male patients. Tumor size is large, associated with distant metastasis and advanced stage. This mutation is found concomitantly with BRAF mutation, and the clinical course is aggressive. Genetic alterations form subsets of PTC with distinct clinicopathological features. Careful assessment of clinicopathological features is considered useful in predicting clinical course and when planning treatment.