Mucinous Cystic Neoplasm : Low-grade

Comments:
Classification of Mucinous Cystic Neoplasms (MCNs): Non-invasive MCNs are classified in a two-tiered system as low-grade MCN and high-grade MCN based on the highest degree of cytoarchitectural abnormalities. This replaces the previous three-tiered system that consisted of MCN with low-grade, intermediate-grade, and high-grade dysplasia. Low-grade and intermediate-grade dysplasia have been rolled into low-grade MCNs. A single tumor often shows a broad range of cytologic and architectural abnormalities, ranging from no atypia to high-grade dysplasia and even foci of invasive carcinoma.

In low-grade MCNs, the tall columnar mucinous epithelium may be arranged as a flat lining or may show papillary projections and crypt-like invaginations. There is some nuclear pseudostratification and slight nuclear enlargement but nuclear polarity is maintained. Occasional mitotic figures may be seen.