CAP Archives: Significance of Proximal Margin Involvement in Low-Grade Appendiceal Mucinous Neoplasms

Thomas Arnason, Michal Kamionek, Michelle Yang, Rhonda K. Yantiss, and Joseph Misdraji (2014) Significance of Proximal Margin Involvement in Low-Grade Appendiceal Mucinous Neoplasms. Archives of Pathology & Laboratory Medicine In-Press.

Early Online Release

Significance of Proximal Margin Involvement in Low-Grade Appendiceal Mucinous Neoplasms

Thomas Arnason, MD; Michal Kamionek, MD; Michelle Yang, MD; Rhonda K. Yantiss, MD; Joseph Misdraji, MD

Department of Pathology, Massachusetts General Hospital and Harvard Medical School, Boston (Drs Arnason, Kamionek, and Misdraji)

Division of Anatomical Pathology, Queen Elizabeth II Health Sciences Centre and Dalhousie University, Halifax, Nova Scotia, Canada (Dr Arnason)

Department of Pathology, University of Massachusetts Memorial Medical Center, Worcester (Dr Yang); and

Department of Pathology and Laboratory Medicine, Weill Cornell Medical College, New York, New York (Dr Yantiss). Dr Kamionek is now located at the Carolinas Pathology Group, Carolinas Medical Center, Charlotte, North Carolina.

Context.— Appendiceal adenomas and low-grade appendiceal mucinous neoplasms (LAMNs) confined to the appendix are cured by appendectomy. However, involvement of the proximal margin raises concern for residual disease. Some patients with a positive margin at appendectomy undergo cecal resection to eliminate a perceived risk for tumor recurrence or dissemination, although that likelihood is assumed rather than demonstrated.

Objective.— To determine whether involvement of the proximal appendiceal resection margin by adenoma or LAMN is a risk factor for local development of recurrence or pseudomyxoma peritonei.

Design.— Appendiceal adenomas and LAMNs confined to the appendix were considered for the study if they showed neoplasia or dissecting mucin at the proximal margin. The presence or absence of residual tumor in cecal resections was determined. Follow-up data were obtained from clinical records.

Results.— 16 patients (14 female, 2 male) with LAMN (n = 15) or adenoma (n = 1) and an involved proximal resection margin were identified, including 9 with neoplastic epithelium within the lumen and 7 with acellular mucin in the appendiceal wall at the margin. Six patients underwent cecal resection and the others were nonsurgically followed. No cecal resection had residual neoplasia. No patient developed recurrence or pseudomyxoma peritonei (mean follow-up, 4.7 years).

Conclusions.— In patients with LAMNs confined to the appendix, involvement of the appendectomy margin by neoplastic epithelium or acellular mucin does not predict recurrence of disease, even without further surgery. A conservative approach to managing these patients can be justified.