TABLE 1.
MSI analysis in 108 appendiceal ADCAs
| ADCA type | Precursor lesion
|
|||||
|---|---|---|---|---|---|---|
| None identified | Adenoma/cystadenoma | Goblet cell carcinoid | ||||
| No. cases | MSI-high | No. cases | MSI-high | No. cases | MSI-high | |
| Signet ring (non-mucinous) | 14 | 0% | 0 | -- | 9 | 0% |
| Mucinous | ||||||
| Well differentiated | 12 | 0% | 8 | 0% | 0 | -- |
| Moderately differentiated | 17 | 0% | 12 | 1 (8%) | 2 | 0% |
| Poorly differentiated | 8a | 0% | 2 | 0% | 1 | 0% |
| Intestinal/non-mucinous | ||||||
| Well differentiated | 0 | -- | 1 | 0% | 0 | -- |
| Moderately differentiated | 7 | 0% | 11 | 0%b | 0 | -- |
| Poorly/undifferentiated | 4 | 2 (50%) | 0 | -- | 0 | -- |
a
One with neuroendocrine features and one with admixed squamous and neuroendocrine carcinoma
b
One of eleven cases was MSI-low (shift in 1 of 7 microsatellite markers) with intact MLH1, MSH2, MSH6, PMS2 immunostains ADCA, adenocarcinoma; MSI, microsatellite instability