Management of Low-Grade Appendiceal Neoplasm

Decision Algorithm Based on Tumor Size and Features

For patients with low-grade appendiceal neoplasm, management should be based on tumor size, location, and histological features, with right hemicolectomy indicated for tumors ≥2 cm or those with high-risk features, as recommended by the National Comprehensive Cancer Network 1, 2
Simple appendectomy is sufficient for well-differentiated tumors <1 cm confined to the appendix with no adverse features, as this is likely curative, according to the National Comprehensive Cancer Network 1
Further resection (right hemicolectomy) should be considered if the tumor breaches the serosal surface, invades the mesoappendix by more than 3 mm, or is located at the base of the appendix, as recommended by the National Comprehensive Cancer Network 1
Right hemicolectomy is indicated for tumors ≥2 cm, even without obvious malignant features, due to higher risk of lymph node metastases and locoregional spread, as recommended by the National Comprehensive Cancer Network 1, 2, 3

For patients with incomplete resection or tumors ≥2 cm, perform abdominal/pelvic CT or MRI to rule out distant disease, and proceed with right hemicolectomy if no distant disease is identified, as recommended by the National Comprehensive Cancer Network 2, 3

For larger tumors or those with adverse features, follow-up every 3-12 months for up to 10 years, and consider chromogranin A as a tumor marker for neuroendocrine tumors, as recommended by the National Comprehensive Cancer Network 3
Perform multiphasic CT or MRI (abdominal/pelvic) during follow-up for larger tumors or those with adverse features, as recommended by the National Comprehensive Cancer Network 3

The National Comprehensive Cancer Network (NCCN) guidelines acknowledge significant controversy for tumors in the 1-2 cm size range, where management recommendations are not clearly defined 4, 5, 6

For appendiceal neuroendocrine tumors (NETs) ≤2 cm confined to the appendix, simple appendectomy is considered sufficient by the NCCN guidelines 4, 5, 6
However, some NCCN member institutions consider more aggressive treatment for 1-2 cm tumors with poor prognostic features such as lymphovascular invasion or mesoappendiceal invasion 4, 5
The presence of favorable features like tumor size below 2 cm, Grade 1 (G1) well-differentiated histology, Ki-67 < 2%, and negative margins are considered low-risk factors 4, 5

Right hemicolectomy (RHC) carries standard surgical risks including anastomotic leak, infection, and prolonged recovery 4
Long-term digestive changes can occur after RHC, including altered bowel habits and potential vitamin B12 malabsorption 4

If RHC is declined, rigorous surveillance is recommended, including imaging with multiphasic CT or MRI of the abdomen/pelvis at 3-6 months, then every 6-12 months 4, 6
Tumor markers such as chromogranin A levels should be considered, although they are not diagnostic, elevated levels associate with recurrence 6
Clinical assessment with complete history and physical examination should be performed at each visit 4, 6