Figure 2

A Pathological examination of the nodule in the right lung reveals that the tumor is composed of spindle-shaped muscle cells and distinct cell borders (hematoxylin and eosin staining, ×2.5). B Pathological examination demonstrated low mitotic activity, little cytological cellular atypia and no tumor cell necrosis (hematoxylin and eosin staining, × 10). C Immunohistochemical staining reveals positive smooth muscle actin (SMA). CD10, CD117 and S-100 were negative in the tumor cells. Positive immunoreactivity for estrogen receptor (ER). D Immunohistochemical staining shows positive estrogen receptor of pulmonary nodules, and the progesterone receptor (PR) suggested that the spindle-shaped cells were uterine smooth muscle cells. E Immunohistochemical staining for smooth muscle actin (SMA) and desmin was strongly positive, suggesting that the spindle-shaped cells were smooth muscle cells.