Rare occurrence of IDH2 mutation in adolescent oligodendroglioma with 1p/19q co-deletion: a case report
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CASE REPORT
Rare occurrence of IDH2 mutation in adolescent oligodendroglioma with 1p/19q co-deletion: a case report Shilpa Rao 1 & Sumitra Sivakoti 1 & Arimappamagan Arivazhagan 2 & Vani Santosh 1 Received: 2 March 2020 / Accepted: 7 April 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Adolescent and young adult gliomas are recently being studied as a distinct group and molecular alterations of oligodendroglioma in this group are not well defined. Few studies conducted on adolescent oligodendroglioma so far have found low frequencies of IDH mutations and 1p/19q co-deletion, which are the hallmark genetic alterations seen in adult oligodendroglioma. In this case report, we demonstrate presence of rare IDH2 mutation and 1p/19q co-deletion in an adolescent oligodendroglioma. Keywords IDH2 . Adolescent . Oligodendroglioma . 1p/19q
Introduction
Case report
Oligodendrogliomas (ODG) are relatively uncommon in children and adolescent age group compared to the adult ODG. In the WHO 2016 classification of central nervous system (CNS) tumors, ODG are defined by IDH mutations and 1p/19q codeletion [1]. Adult ODG harbor IDH1 (R132H) mutations in > 90% of cases with IDH2 mutations seen rarely even in this age group. There is no definitive molecular signature for adolescent ODG, and the frequencies of IDH mutation and 1p/ 19q co-deletion are low as reported by few studies [2–7]. We report a case of an adolescent ODG with rare IDH2 mutation and 1p/19q co-deletion.
An 18-year-old boy presented with complaints of headache for 2 years, blurring of vision, vomiting, and dizziness for a year. He had no neurological deficits on examination. Imaging revealed a large intra-axial lesion involving the right temporal lobe, hippocampus, and para-hippocampal gyrus, extending into ambient cistern medially, atrium and occipital horn posteriorly, causing mass effect. The lesion was hypointense on T1 weighted and hyperintense on T2 weighted images, enhancing mildly on post-contrast, features that suggest highgrade glioma in adults (Fig. 1a–f). Patient underwent right temporal craniotomy and near total resection of the tumor. Histopathological examination revealed a diffusely infiltrating monomorphic glial neoplasm composed of cells with an oligodendroglial morphology (Fig. 2a, b). There was minimal nuclear atypia with occasional mitosis favoring a lowgrade glioma. Microcalcification was noted. There was no biphasic histological pattern, Rosenthal fibers, or eosinophilic granular bodies, thus excluding the close differential diagnosis of pilocytic astrocytoma. Similarly, dysembryoplastic neuroepithelial tumor (DNET) was ruled out due to lack of typical architectural pattern and floating neurons. Immunohistochemistry (IHC, Fig. 2c–f) revealed the tumor cells to be immunopositive for S-100, variably positive for GFAP and immunonegative for IDH1 (R132H), epithelial membrane antigen (EMA), and p53. ATRX expression was retained. Based on histomorphology and IHC, the diagnosis of diffuse glioma, NOS (oligodendroglial phe
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