Postoperative photomicrographs of lesion in PSH portion. (a) the tumor was composed of sheets of round cells with scattered surface cuboidal cells forming small tubules. (b) The surface cuboidal cells demonstrated vacuolated and foamy cytoplasm with focal mild nuclear atypia (black arrow). The round cells showed uniform, medium-size polygonal nuclei with moderate amounts of pale, eosinophilic or clear cytoplasm (black arrowhead). (c) In some area, papillary pattern with hyalinizing stalks could be obsreved. Both surface cuboidal cells and round cells could be found in this structure. (d) Immunohistochemically, positivity of surface cuboidal cells, but negativity of round cells for pancytokeratin was found in tumor. (e) Both surface (black arrow) and round cells (black arrowhead) showed strongly positive for TTF-1. (f) A focal weak positivity of round cells (black arrowhead) for synaptophysin was observed in this portion, but the surface cells (black arrow) showed negative for Syn. (a, H&E staining with original magnification of 200 ×; b-c, H&E staining with original magnification of 400 ×; d-f, immunohistochemical staining with original magnification of 400 ×).