Fig. 3

Macroscopic appearance and histological examination of the resected specimen. a No lesions were found on the mucosal surface. b There were sinus-like spaces in the submucosal, proper muscular, and subserosal layers of the appendix, as indicated by hematoxylin and eosin staining. c Some of these spaces were filled with blood. d CD34-positive cells were lined with vascular spaces on immunohistochemistry analysis