Fig. 2

A The tumor cells arranged in irregular nests, cords, trabeculae, and tubular shapes with loose mucinous stroma and focal stroma hyalinized (red arrow) (HEx 40). B Atypical small-to-medium-sized epithelioid cells with light eosinophilic to clear cytoplasm lacking significant pleomorphism and mitotic activity arranged in irregular nests, cords, trabeculae, and tubular patterns (red arrow) with a loose myxoid stroma (C) (HEx 200). Focally, the tumor cells appeared to be connected to the basal layer of the bronchial epithelium. D Immunohistochemistry revealed that the tumor cells were positive for CK7. E Immunohistochemistry revealed that most of the tumor cells were positive for p40