Fig. 4
Pathological findings. a Macroscopic findings revealed two squamous cell carcinomas. One was located in the upper thoracic esophagus, and the other was located in the middle thoracic esophagus. b, c Hematoxylin and eosin staining of the tumor located in the b unirradiated upper thoracic esophagus and c previously irradiated middle thoracic esophagus. The dashed black lines point to the area of each tumor. Black and yellow arrows show the thickness of the muscularis propria and adventitia, respectively. d, e Microscopic findings of the adventitia of the d unirradiated normal esophagus and e previously irradiated lesion (original magnification × 200). The adventitia of the irradiated esophagus had severe fibrosis and thickness compared to the normal esophagus located outside the irradiation field