A tall-cell variant of a papillary thyroid carcinoma (PTC) was diagnosed in the thyroid, but the bone lesion was a metastasis from BC, with estrogen receptor (ER) and progesterone receptor (PR) expression levels of 0% and 20%, respectively, and no HER2 amplification/overexpression (Figure 1). Here, ESR1 is linked to differentiated thyroid carcinoma.