Fig. 3

Macroscopic and microscopic findings of the resected tumor. a Macroscopic findings revealed a 28 × 20 × 11 mm³ brown–red tumor with a smooth cut surface. b Microscopic findings revealed papillary architecture with focal small aggregates of mesothelial cells. c Tumor cells were positive for cytokeratin 5/6. d Tumor cells were partially positive for calretinin. e Tumor cells were negative for carcinoembryonic antigen. f Tumor cells were negative for thyroid transcription factor-1. g Tumor cells were negative for cluster of differentiation 34. h Tumor cells were negative for signal transducer and activator of transcription 6