Fig. 1

Histology of thyroid nodules. A Microcarcinoma (H&E). The nuclei of tumor cells showed a ground glass-like appearance, and tumor cells were surrounded by a sclerotic stroma. B Papillary carcinoma (H&E). Tumor cells, whose nuclei exhibited a ground glass-like appearance, formed irregular papillary structures. C Follicular adenoma (H&E). Follicles composed of tumor cells that exhibited mild nuclear atypia, but not capsular invasion, were observed (fc, fibrous capsule). D Minimally invasive follicular carcinoma (H&E). Tumor cells that exhibited mild atypia invaded the fibrous capsule (fc, fibrous capsule; arrows, capsular invasion). E Undifferentiated carcinoma (H&E). Polymorphous atypical short spindle-shaped cells that exhibited loose cell-cell adherence were arranged in fascicular structures or diffusely distributed. F Adenomatous goiter (H&E). Hyperplastic follicular cells without atypia were detected. Follicles contained colloid