Final diagnosis: Benign entrapped neuroendocrine cells (islet cells) due to chronic pancreatitis associated with IPMN.

These islet cells show atypia with hyperchromasia and arrangement in small nests, single lines or individual cells, which may mimic invasive carcinoma. Similar changes can be noted in adjacent reactive lobules. 

The following picture shows a transition from residual islets (right side), to small nests (middle), and to individual cells (left).

 Immunostains for Synaptophysin

名称：图1
描述：图1

名称：图2
描述：图2

 倾向诊断为:

1)IPMN伴PanIN 2;

2) 慢性胰腺炎伴胰岛增生;

鉴别诊断:

1) IPMN伴低分化导管腺癌;

2) IPMN伴胰腺内分泌肿瘤(PEN)

3) IPNM+MEN1

 看这张图片，就不是一个良性的肿瘤。这么大的细胞内分泌肿瘤可能性也比较小。这个肿瘤应该和黏液性上皮有联系。