Appendiceal Mucinous Neoplasm with Low Risk of Recurrence
Definition
- Appendiceal neoplasm with features of mucinous adenoma but with extra-appendiceal acellular mucin
Alternate/Historical Names
- Borderline mucinous tumor
- Disseminated peritoneal adenomucinosis
- Low grade mucinous neoplasm (WHO preferred term, includes low and high risk of recurrence neoplasms, see Controversy)
- Mucinous neoplasm of low malignant potential
Diagnostic Criteria
- Features of mucinous adenoma (see detailed adenoma criteria)
- Simple mucinous columnar epithelium
- Low grade dysplasia
- Sessile, usually circumferential, lining of appendiceal luminal surface
- Frequent mucin dissection of the wall
- May contain neoplastic epithelium within intramural mucin only
- No clear direct invasion of the wall by neoplastic epithelium
- EXCEPT either of the following is present
- Extra-appendiceal acellular mucin, or
- Mucinous adenoma with transection of neoplasm at the margin of resection
- Specimen should be entirely submitted before this diagnosis is made
- A very low percentage will recur
- Reported rates 4-8% but none of the recurrrent cases were entirely embedded for sections
- No deaths reported
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
Original posting/updates : 10/7/10, 2/10/12, 3/6/12
