Table 3.
Patients with Lynch Syndrome Stratified by the Presence of DNA Mismatch Repair (MMR) Protein Deficient Colonic Crypts
| Clinicopathologic Features | Lynch Syndrome with MMR Deficient Non-Neoplastic Colonic Crypt N (%) | Lynch Syndrome without MMR Deficient Non-Neoplastic Colonic Crypt N (%) | p-value |
|---|---|---|---|
| No. of Cases | 18 | 34 | NA |
| Mean Age in years (range) | 57 (27–79) | 51 (28–80) | 0.1 |
| Gender, Male/Female | 10 (56) / 8 (44) | 17 (50) / 17 (50) | 0.9 |
| Location | |||
| Right Colon | 14 (78) | 18 (53) | 0.08 |
| Left Colon / Rectum | 4 (22) | 16 (47) | |
| MMR IHC Pattern in Carcinoma | |||
| Intact expression of all 4 proteins | 0 (0) | 1 (3) | 0.7 |
| MLH1 and PMS2 Loss | 4 (22) | 9 (26) | |
| MSH2 and MSH6 Loss | 7 (39) | 17 (50) | |
| Isolated MSH6 Loss | 4 (22) | 4 (12) | |
| Isolated PMS2 Loss | 3 (17) | 3 (9) | |
| Germline Mutation Analysis | |||
| MLH1 pathogenic variant present | 4 (22) | 9 (27) | 0.6 |
| MSH2 pathogenic variant present | 7 (39) | 18 (53) | |
| MSH6 pathogenic variant present | 4 (22) | 4 (12) | |
| PMS2 pathogenic variant present | 3 (17) | 3 (17) | |
| Mean length of colonic mucosa evaluated by IHC in millimeters (range) | 136 (21–336) | 88 (5–244) | 0.03 |
| Mean estimated number of colonic crypts evaluated by IHC (range) | 1508 (233–3733) | 981 (56–2711) | 0.03 |
MMR, mismatch repair; IHC, immunohistochemistry