PAX8 and neoplasm: The anaplastic thyroid carcinoma (undifferentiated carcinoma) usually has diverse morphology, obvious cell atypia, easy to see mitotic images, immunohistochemical PAX8 positive (36–76%), but this case has obvious clear cells, mitotic images are rare, PAX8 Negative, but GATA3 positive, which further proves that the tumor originates from the parathyroid gland.