Johns Hopkins Pathology

 
Key Points:
  • Two types of papillary projections
  • Intestinal and Pancreatobiliary
Images: Papillary architecture | Colloid Cancer |

IPMN's may appear similar to mucinous cystic tumors. However, IPMN's involve the ducts of the pancreas and exhibit no ovarian stroma-- two characteristics that distinguish them from mucinous cystic neoplasms.

Papillary projections associated with IPMN's appear in two types of patterns: intestinal type papillae, lined by a border of pseudostratified, tall columnar cells with occasional Goblet cells, and pancreatobiliary type papillae, seen as complex branches with cuboidal cells and large nucleoli. Also seen in IPMN's are paneth cells and neuroendocrine cells.

IPMN's are graded based on the level of cellular atypia they exhibit. Adenomas are considered to have simple mucinous columnar cells, low nucleus-to-cytoplasm ratio, apical cytoplasmic mucin, diffuse and fine chromatin pattern, and no cytological atypia. Borderline cases exhibit pseudostratified pencil-shaped cells, a lack of fusion of micropapillae, and cells with mild to moderate atypia. Carcinoma in situ is marked by severe cellular atypia and fusion of papillae.

When an invasive carcinoma is present, it is often an invasive colloid carcinoma.

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