Representative morphological and expression of the two metabolic enzymes. FTC (A) and FTA (B); Hematoxylin and eosin (H&E) staining for (A1) FTC, (A2) FASN, and (A3) iPLAs, which showed weak or moderate cytoplasmic staining. H&E staining for (B1) FTA, (B2) FASN, and (B3) iPLAs showed strong positive staining. (C,D) show the metabolic enzyme expression in borderline thyroid tumors. (C1,D1) H&E stained for an NIFTP and a UMP, (C2,D2) showed FASN staining, and (C3,D3) showed iPLAs staining. NIFTP, non-invasive follicular thyroid neoplasm with papillary-like nuclear features; UMP, uncertain malignant potential.