Figure 6

Microscopic examination. A, B, Heterotopic pancreas in the duodenal submucosa and muscularis propria around the minor papilla was noted. There were uniform and round-shaped cells in or around the heterotopic pancreas and they were arranged in a solid nest or tubular pattern. These findings were suggestive of a carcinoid tumor. There was vascular invasion, but no perineural invasion was noted. (H&E stain A: ×10, B: ×100) C, D, According to immunohistochemical staining, the tumor cells were immunoreactive with neuroendocrine markers, such as synaptophysin and chromogranin.(C:Synaptophysin stain ×100; D: Chromogranin stain ×100)