ESR1 and neoplasm: The immunohistochemical (IHC) results indicated the presence of spindle tumor cells with the following markers: vimentin (+), CD10 (+), cyclin D1 (+) (Figure 3), Ki-67 (40% +), calponin (-), CD34 (-), CK (-), Desmin (-), estrogen receptor (ER; -), progesterone receptor (PR; -), S100 (-), and smooth muscle actin (SMA; -).