Mucinous Cystic Neoplasm of the Pancreas

Definition

Cystic mucinous neoplasm with ovarian type stroma and lacking communication with the pancreatic ducts

Grossly or radiographically visible lesion
- 95% in body or tail of pancreas
Usually multilocular
- Cysts variably sized
  - Usually 1 to several cm
- Frequently one dominant thick walled cystic structure
  - Frequently contains multiple smaller daughter cysts in wall
Lined by tall columnar cells
- Basal nuclei
- Abundant intracellular mucin
  - Mucin may be depleted in high grade lesions
- May be partially denuded or lined by atrophic cells
- Goblet cells frequently admixed
- Scattered neuroendocrine cells in half of cases
- Focal gastric, intestinal or squamous differentiation may be seen
- Varying degrees of cytologic atypia and architectural complexity
  - See Grading
Ovarian type stroma
- Inner layer moderately to densely cellular
  - Spindled cells with bland round to oval nuclei
  - May be luteinized
  - May be sparse or absent in patients >60
  - May be sparse in large lesions
- Outer layer densely collagenous
- May calcify
Lacks communication to pancreatic ducts
Virtually all cases in females
Separated into adenoma grade, borderline grade, carcinoma in situ grade
- See Grading for specific features
Up to 1/3 have associated carcinoma
- Usually ductal
- Not colloid (mucinous)
- Entire lesion should be submitted to evaluate for associated carcinoma
- Unusual if lesion < 3cm
Rare cases with sarcomatous stroma
- With or without heterologous elements

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/last update: 2/1/07, 1/17/115