Fig. 2

Postoperative pathology. A H&E staining reveals numerous tumor cells. And tumor cells have oval or round nuclei with amphophilic to eosinophilic cytoplasm and minimal mitotic activity. Tumor cells surrounding capillary-sized vessels (red arrows) (H&E, ×20 magnification). B, C IHC staining for SMA and h-caldesmon are positive. D Ki67 index is less than 3%