From the Research
A right hemicolectomy should be offered for High-grade Appendiceal Mucinous Neoplasm (HAMN) discovered on appendicectomy when there is evidence of positive margins, perforation with peritoneal spillage, lymph node involvement, or tumor size greater than 2 cm, as indicated by the most recent and highest quality study 1.
Key Indications for Right Hemicolectomy
- Positive margins
- Perforation with peritoneal spillage
- Lymph node involvement
- Tumor size greater than 2 cm
- Invasion beyond the muscularis propria (T3 or T4)
- Lymphovascular or perineural invasion
- Base of the appendix involvement
- Histopathology revealing high-grade dysplasia or adenocarcinoma components
Rationale for Right Hemicolectomy
The procedure is indicated to ensure complete oncological clearance, as HAMNs have malignant potential and may have already spread to regional lymph nodes or adjacent structures. The procedure involves removing the terminal ileum, cecum, ascending colon, and associated lymph nodes to achieve adequate margins and proper staging.
Surveillance Alone
If the HAMN is confined to the appendix with negative margins, less than 2 cm in size, and without concerning features, surveillance alone may be appropriate as the risk of lymph node metastasis is low in these cases, as suggested by 2 and 1.
Evidence-Based Decision Making
The decision to offer a right hemicolectomy should be based on the most recent and highest quality evidence, which suggests that a tumor size greater than 2 cm is a significant risk factor for lymph node metastasis 1. Additionally, the presence of lymphovascular invasion should be considered a minor criterion for right hemicolectomy 1.