We report on a case with constitutional mismatch repair deficiency caused by a novel MSH6 mutation leading to a T-cell lymphoma and colonic adenocarcinoma at six and 13 years of age, respectively.
The patient's adenocarcinoma of the colon and IPMN of the pancreas showed identical immunohistochemical staining profiles with loss of expression of MSH2 and MSH6 proteins and high levels of microsatellite instability.