Pediatric high-grade gliomas (HGG) are rare aggressive tumors that present a prognostic and therapeutic challenge. Diffuse midline glioma, H3K27M–mutant is a new entity introduced to HGG in the latest WHO classification. In this study we evaluated the presence of H3K27M mutation in 105 tumor samples histologically classified into low-grade gliomas (LGG) (n = 45), and HGG (n = 60). Samples were screened for the mutation in histone H3.3 and H3.1 variants to examine its prevalence, prognostic impact, and assess its potential clinical value in limited resource settings. H3K27M mutation was detected in 28 of 105 (26.7%) samples, and its distribution was significantly associated with midline locations (p-value < 0.0001) and HGG (p-value = 0.003). Overall and event- free survival (OS and EFS, respectively) of patients with mutant tumors did not differ significantly, neither according to histologic grade (OS p-value = 0.736, EFS p-value = 0.75) nor across anatomical sites (OS p-value = 0.068, EFS p-value = 0.153). Detection of H3K27M mutation in pediatric gliomas provides more precise risk stratification compared to traditional histopathological techniques. Hence, mutation detection should be pursued in all pediatric gliomas. Meanwhile, focusing on midline LGG can be an alternative in lower-middle-income countries to maximally optimize patients’ treatment options.
Objective: To evaluate the status of C-MYC protein expression and Ki-67 proliferative index and to clarify their role in predicting relapse of diffuse large B cell lymphoma (DLBL). Materials and Methods: A retrospective study conducted on 50 cases diagnosed as DLBL in a 3 years’ time period from January 2014 till December 2016, collected from the archive of Pathology Departments of the National Cancer Institute Cairo - Egypt, Misr University for Science and Technology and private labs of authors. The diagnosis of DLBL for all cases, both nodal and extranodal, was confirmed by histopathologic examination and immunophenotyping. Automated immunohistochemical staining using antibodies against C-MYC protein and MIB-1 was used to evaluate the C-MYC expression in tumor cells and to assess their proliferative ability by calculating Ki-67 labelling index. The relation between the percentage of C-MYC protein expression, Ki-67 proliferative index, clinical data and the relapse status during the follow up period were analyzed. Results: A total of 50 cases of DLBL in both nodal and extra-nodal sites were included. Twenty-three cases (46%) were expressing the C-MYC protein, and 29 cases (58%) showed high Ki-67 proliferative index. Twenty-two cases (44%) relapsed during the follow-up period. Positive C-MYC protein expression was significantly associated with high Ki-67 proliferative index. C-MYC protein expression and high Ki-67 proliferative index were independently associated with disease relapses in 81.8% and 86.4% of cases respectively. Cases with combined C-MYC protein expression and high Ki-67 proliferative index showed statistical prediction of relapse in 81.8% of cases. Conclusion: C-MYC protein expression and high Ki-67 proliferative index were independently associated with relapse of diffuse large B cell lymphoma. Furthermore, the combined positive C-MYC protein expression and high Ki-67 proliferative index is better than a single positive test in predicting relapses among DLBL patients.
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