Intraductal Papillary Mucinous Neoplasm of the Pancreas

Definition

Grossly and/or radiographically visible pancreatic intraductal mucinous epithelial proliferation that forms papillary projections

Grossly visible lesion
- Involves main duct or branch ducts
- Variable duct dilation
  - Usually >1 cm diameter
Predominantly papillary
- Rarely flat
Four types recognized
- Gastric type lined by tall columnar foveolar type cells
  - Small basal nuclei
  - Scattered goblet cells may be seen
  - Usually seen in IPMN involving branch ducts
- Intestinal type lined by columnar cells with apical mucin
  - Pseudostratified elongated nuclei
  - Goblet cells may predominate
  - Usually seen in IPMN involviing main duct
- Pancreatobiliary type lined by cuboidal cells with amphophilic cytoplasm
  - Round hyperchromatic nuclei
- Oncocytic type lined by cells with abundant eosinophilic granular cytoplasm
  - Large round nuclei with prominent nucleoli
  - Frequenly with cribriform intracytoplasmic lumina
  - Considered by some to be a separate lesion, see details at Intraductall Oncocytic Papillary Neoplasm
Noninvasive
Varying degrees of cytologic atypia and architectural complexity
- See Grading
IPMN associated with invasive carcinoma
- Up to 40% of IPMN associated with invasive carcinoma
- Invasive carcinoma most often associated with IPMN carcinoma-in-situ grade
- 60% invasive ductal carcinoma
- 30% invasive colloid carcinoma
  - >80% mucin pools containing neoplastic epithelial cells
- 5-10% invasive anaplastic carcinoma
- Entire lesion should be submitted to evaluate for invasion

Reetesh Pai MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates: 1/1/07, 1/2/12