Mucinous Cystic Neoplasm

Epidemiology:

• Women almost always
• Avg age 50
• Older is more likely malignant

Common sites:

• Body or tail (almost always)

Gross features:

• Thick, tenacious mucin

Histologic features:

• Cyst lining is columnar mucinous
• Underlying ovarian-like stroma (required by WHO)
• Not connected to main duct system
• Benign / “low-grade dysplasia”:
• no significant cytologic atypia
• no significant architectural complexity
• borderline / “moderate dysplasia”:
• significant cytologic atypia
• significant architectural complexity
• no invasion
• carcinoma / “high-grade dysplasia”:
• more atypia
• more architectural complexity
• can be invasive (invasive mucinous cystadenocarcinoma) or non-invasive

Immunophenotype:

Marker:	Sensitivity:	Specificity:
CK7
CK20 (neg)	Often
ER / PR
CEA
CA125 (double check this)

Molecular features:

Other features:

• non-invasive carcinoma / “high-grade dysplasia” do very well if completely resected
• invasive do much worse than non-invasive (must section these very well!)
• NOT associated with pseudomyxoma peritoneii

References:

• Robbins 2005