Molecular and histologic characteristics of pseudoprogression in diffuse gliomas

During the 6 month period following chemoradiotherapy, gliomas frequently develop new areas of contrast enhancement, which are due to treatment effect rather than tumor progression. We sought to characterize this phenomenon in oligodendrogliomas (OG) and mixed oligoastrocytomas (MOA). We reviewed the imaging findings from 143 patients with a WHO grade II or III OG or MOA for evidence of pseudoprogression (PsP) or early tumor progression. We characterized these cases for 1p/19q codeletions by FISH, IDH1 R132H mutation by immunohistochemistry, and TP53, ATRX, and EGFR mutations by next generation sequencing. We then reviewed the pathologic specimens of the patient cases in which a re-resection was performed. We found that OG and MOA that are 1p/19q intact developed PsP at a higher rate than tumors that are 1p/19q codeleted (27 vs. 8 %). Moreover, IDH1 wild-type (WT) tumors developed PsP at a higher rate than IDH1 R132H cases (27 vs. 11 %). Patients with ATRX or TP53 mutations developed PsP at an intermediate rate of 21 %. Ten patients in our cohort underwent a re-resection for early contrast enhancement; these tumors were predominantly 1p/19q intact (90 %) and had a low rate of IDH1 R132H mutation (50 %). 8 of 10 tumors demonstrated primarily treatment effects, while the remaining 2 of 10 demonstrated recurrent/residual tumor of the same grade. Early contrast enhancement that develops during the first 6 months after chemoradiotherapy is typically due to PsP and occurs primarily in OG and MOA that are 1p/19q intact and IDH WT.

Morphologic spectrum of glial tumors: an increased trend towards oligodendroglial tumors in Pakistan

Background

Glial tumors are most common brain tumors in our population. While the exact etiology and pathogenesis is unknown, the evaluation of current trends in the frequency and morphology of glial tumors is imperative to constitute better diagnostic and treatment protocols. Data pertaining to frequency and spectrum of glial tumors is scarcely available in our population. The aim of this study was to determine the morphologic spectrum of glial tumors prevalent in our population.

Method

126 cases of glial tumors were retrospectively analyzed over a period of 5 years. Patients from all age groups and both genders were included in this study. Glial tumors were classified and graded according to WHO classification.

Results

Glial tumors were more common in males with a sex ratio of 2:1 and mean age of 38.26 years. Astrocytomas were most common glial tumors (51.6%) followed by oligodendrogliomas (23%). Glioblastoma was the most frequent astrocytic tumor and was incomparably frequent in older age group.

Conclusion

In our study, Oligodendrogliomas and mixed oligoastrocytomas represent major pattern of disease in comparison with available regional data. Knowledge of these changing trends and patterns of glial tumor morphology and frequency can help in improvements and applications of newly emerging diagnostic and treatment modalities.