Clinicopathological And Immunohistochemical Heterogeneity Analysis Of Microsatellite Highly Instable Colorectal Cancer

ObjectiveTo explore the clinicopathological and immunohistochemical heterogeneity of microsatellite highly instable colorectal cancer,and hence to improve the understanding and diagnosis of this disease.MethodThe clinicopathological data of 33 patients with known microsatellite stability were retrospectively analyzed.The histological morphology and immunohistochemical phenotype of MLH1 MSH2 MSH6 PMS2 were observed,and related literatures were reviewed.For the cases with heterogeneous expression of MLH1 MSH2 MSH6 PMS2 immunohistochemistry,the positive percentage of tumor cells was estimated respectively,and the corresponding gene test results of the patients were combined for comprehensive analysis.ResultAmong the analyzed cases,there were 25 cases of microsatellitestable colorectal cancer and 8 cases of microsatellite instable colorectal cancer.There were 18 males and 14 females,aged 37-74 years,with an average age of 52 years.The study showed that repeated abdominal pain and changes in stool characteristics were the primary clinical symptoms.These symptoms were mostly accompanied by the presence of an ulcer/cauliflower-shaped mass that occupies the intestine.Microscopically,the glandular gland or cells replaces the normal intestinal mucosa,and some pathological changes such as mucus differentiation,myeloid differentiation,and "Crohn"-like lymphocyte infiltration are observed.Immunohistochemically,In 25 cases of microsatellite stabilized colorectal cancer,4 mismatch repair proteins MLH1 MSH2 MSH6 PMS2 all showed positive nuclear staining;In 8 cases of microsatellite highly instable colorectal cancer,there was at least one protein staining nucleus with a lack of consistency in the four mismatch repair proteins in cancer cells;but the MSH6 protein staining of case 3 and case 8,and the MSH2 and MSH6 protein staining of case 7 were also showed heterogeneous absence(partial absence).Respectively,the positive percentage of tumor cells were 70%,20% and 80%,and the corresponding gene test results were: no mutation,no mutation,no mutation.Ki67 index: 35%-90%.ConclusionThe clinical,pathological and molecular characteristics of microsatellite highly instable colorectal cancer are different frommicrosatellite stable colorectal cancer;Mismatch repair protein immunohistochemistry heterogeneity does exist in microsatellite highly instable colorectal cancer,but the specific positive rate cutoff value needs to be accumulated in a large number of cases to explore.