Figure 2

Histological examination (hematoxylin-eosin). (A) The lesion located under the enteric mucosa with diffusely infiltrative tumor cells without obvious mucosal destruction (Objective × 4); (B) The tumor cells showed markedly cytologic atypia with large eosinophilic nucleoli, abundant mitotic figures and moderate cytoplasm, however, without visible melanin pigment (Objective × 40).