Stanford School of Medicine

Surgical Pathology Criteria

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Mucinous Adenoma / Cystadenoma of the Appendix


  • Circumferential lining of appendiceal luminal surface by low grade dysplastic epithelium

Diagnostic Criteria

  • Simple adenomatous mucinous columnar epithelium
    • Focal nuclear stratification may be present
    • Contains occasional goblet cells
    • May be cuboidal or flat from compression
    • Low grade dysplasia
      • Mitotic figures, if present, are not atypical
      • Must not exhibit high grade dysplasia
        • No high grade cytologic features or cribriform architecture
  • No invasion
    • No direct invasion of muscular wall by jagged neoplastic glands
      • Muscularis mucosae may be attenuated by distension making evaluation difficult
    • Intramural mucin containing epithelium may be present
  • No extra-appendiceal mucin with or without epithelium
  • Proximal margin of appendix must not be involved
  • Sessile, usually circumferential, lining of appendiceal luminal surface
    • May be undulating or villous
  • Commonly associated with luminal dilation
    • Common cause of mucocele
    • Wall of appendix may calcify
  • Specimen should be entirely submitted before this diagnosis is made
  • Myxoglobulosis may be seen occasionally
    • Pearl-like globules of acellular laminated mucin surrounding an amorphous granular and mucinous core
      • 1-10 mm
      • May calcify peripherally
    • Present in lumen or periappendiceal tissue
  • May be associated with colorectal adenoma or carcinoma and ovarian mucinous tumor
    • Justifies consideration for screening
  • Benign, does not recur after resection
  • Usual colonic type adenomas are extremely rare
Teri A Longacre MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates : 10/7/10

Differential Diagnosis

Appendiceal Mucinous Neoplasms
Mucinous Adenoma/Cystadenoma Mucinous Low Risk of Recurrence Mucinous High Risk of Recurrence Mucinous Adenocarcinoma
No extra-appendiceal mucin No epithelium in extra-appendix mucin Epithelium present in extra-appendiceal mucin Epithelium may be present in extra-appendiceal mucin
Non-invasive epithelium may be present in intramural mucin Non-invasive epithelium may be present in intramural mucin Non-invasive epithelium may be present in intra and extramural mucin Invasion by jagged neoplastic glands
Margin of resection must be clear Margin may be involved Margin may be involved Margin may be involved
Benign, no recurrences Very few recur, 0% mortality Frequently recur, 50% 5 year, 20% 10 year survival <10% 10 yr survival

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