Sessile Serrated Polyp/Adenoma of the Appendix
Supplemental Studies
No studies currently useful for diagnosis, but following may shed some light on the nature of serrated lesions of the appendix (based on Yantiss 2007)
- CpG island DNA hypermethylation is evident in about half of appendiceal hyperplastic polyps, sessile serrated adenomas, traditional serrated adenomas, and SSA with dysplastic foci (SSAD)
- MLH1 staining is lost in about 50% of all four
- Nevertheless, MSI is extremely rare in all four
- MGMT staining is lost in about 50% of HP, SSA and TSA, and 100% of SSAD
- BRAF is mutated in 20-25% of HP, TSA and SSAD and 47% of SSA
- KRAS is mutated in 20-40% of all four
- Only 1 of 4 carcinomas associated with SSA was MSI high
- No clear pattern of progression to support a serrated neoplasia pathway as in the colorectum
