What histologic features seen in CRCs can predict MSI H?
- These tumors are usually right sided, show a medullary or syncytial growth pattern, have mucinous or signet ring cell features, are poorly differentiated, and show lymphocytic infiltration.
- Also, a Crohn-like reaction (nodular lymphoid aggregates) is seen beyond the advancing edge of the tumor.
- These features, along with the age at diagnosis, are used to determine the microsatellite instability by pathology score.
