Microscopic description and IHC:
As previously mentioned, the cyst does not communicate with pancreatics ducts. It is lined by hemorrhagic soft mucosa and multiple smaller cysts. No obvious papillary formation is seen.
Most of the cyst is lined by cuboidal and focally tall mucin producing cells overlying ovarian type stroma. Occasional low grade dysplasia are seen.
The stroma is positive for CD10 and focally positive for inhibin.
Discussion:
Mucinous cystic neoplasms are one of the three precursor lesions to pancreatic adenocarcinoma. The other two being pancreatic intraepithelial neoplasia (PanIN) and Intraductal papillary mucinous neoplasm (IPMN). It occurs almost exclusively in females, usually large (mean size 10 cm), and usually found in the body or tail of the pancreas. Unlike PanIN and IPMN, it does not communicate with pancreatic ductal systems. It is composed of an epithelial lining and an underlying ovarian type stromal component, which can be stained with CD10, inhibin, ER, or PR. Surgical resection is curative.