Mucinous Cystic Neoplasm : Microscopic
Microscopic Features of Mucinous Cystic Neoplasm (MCN) of Pancreas: MCNs are lined by tall columnar mucinous epithelium with small basally located nuclei. The epithelium is arranged as a flat lining or may show simple papillary foldings and crypt-like invaginations. There is no cytologic atypia. Mitotic activity is not increased. Some foci have cuboidal ductal type (non-mucinous) epithelium with eosinophilic cytoplasm. Scattered goblet cells are usually seen. With immunohistochemical markers, most cases can be shown to have a few endocrine cells. An important diagnostic feature of MCNs is the presence of distinctive ovarian-type stroma beneath the epithelium. It consists of densely packed spindle cells with round to oval nuclei and scant cytoplasm. The stroma may show clusters of epithelioid cells with clear or eosinophilic cytoplasm, resembling luteinized cells. The stroma may be hypocellular, hyalinized, or present in only few areas in some cases. It may also decrease in the areas of high-grade dysplasia or invasive carcinoma.