Here we present a co-occurrence of a non-typical presentation of DIG/DIA and multiple sclerosis in a 13-year-old female. Our case highlights how a thorough investigation prior to treatment is needed in patients with such condition to choose proper management for better prognosis.

Desmoplastic infantile astrocytomas and gangliogliomas (DIA/DIGs) are rare brain tumours of infancy. A distinctive feature of their histopathology is a combination of low-grade and high-grade features. Most DIA/DIGs can be surgically resected and have a good prognosis. However, high-grade features often dominate recurrent tumours, some of which have a poor outcome. In this study, we test the hypothesis that low-grade and high-grade areas in DIA/DIGs have distinct molecular characteristics. Tissue samples from microdissected low-grade and high-grade areas in 12 DIA/DIGs were analysed by DNA methylation profiling, whole exome sequencing, RNA sequencing and immunohistochemistry to search for potential differences at multiple molecular levels. Copy number variants among tumours and between the two morphologically distinct areas were infrequent. No recurrent genetic alterations were identified across the tumour series, and high-grade areas did not have additional genetic alterations to explain their distinct morphology or biological behaviour. However, high-grade areas showed relative hypomethylation in genes downstream of the transcription factors SOX9 and LEF1 and evidence of a core SOX9 transcription network alongside activation of the BMP, WNT and MAPK signalling pathways. This study contributes to our knowledge of molecular genetic alterations in DIA/DIGs, uncovers molecular differences between the two distinct cell populations in these tumours and suggests potential therapeutic targets among the more proliferative cell population in DIA/DIGs.

Desmoplastic infantile astrocytoma/ganglioglioma (DIA/DIG) are rare primary glioneuronal tumors that comprise 0.5% to 1.0% of all intracranial tumors. While BRAF mutation is found in up to 50% of pediatric gangliogliomas, data for DIA/DIGs is limited. This study was carried out to evaluate the frequency of BRAF V600E mutation in DIA/DIG. All cases of DIA/DIGs diagnosed over 7 years (2010-2016) were reviewed retrospectively. The clinical, radiological and histopathological characteristics of these patients were evaluated along with immunohistochemical analysis for glial and neuronal markers. We evaluated presence of BRAF V600E mutation by Sanger sequencing and immunohistochemistry using monoclonal antibody against clone VE1. Eight cases of desmoplastic infantile astrocytoma/ganglioglioma (6 DIGs and 2 DIAs) were evaluated. Four cases were of infantile type (age 10 months-2 years) and 4 cases of non-infantile type (age 10-14 years). BRAF VE1 immunohistochemistry (IHC) was positive in four cases (two DIG and two DIA). All these four cases also showed heterozygous BRAF V600E mutation (T replaced by A at nucleotide position 1799). Sequencing didn't detect BRAF mutation in any additional case. All four cases harboring this mutation were non-infantile (10-14 years). Cases with infantile presentation didn't carry this mutation. None of the cases showed recurrence on follow-up. Thus BRAF V600E mutation is common in desmoplastic non-infantile astrocytoma/ganglioglioma, but does not affect the prognosis. Identification of BRAF status opens the possibility of targeted therapies for the subset of cases that clinically progress post-resection.

Desmoplastic infantile astrocytoma (DIA) and desmoplastic infantile gangliogliomas (DIGs) are rare, massive, cystic and solid tumors of infants usually found in superficial cerebral hemispheres. They manifest prominent desmoplastic stroma, admixed neoplastic astrocytes, primitive-appearing small cells, and additional neoplastic ganglion cells in the case of DIGs. While v-Raf murine sarcoma viral oncogene homolog B (BRAF) mutation is found in up to 50% of pediatric gangliogliomas, two recent studies found that it was rare in DIA/DIGs; we sought to assess BRAF status in DIA/DIGs from our institution. Departmental files from 2000 to 2016 were reviewed to identify cases. Clinical, neuroimaging, histological, and immunohistochemistry (IHC) features were assessed; the latter included IHC for astrocytic and neuronal markers and BRAF VE1. BRAF mutational assessment by Sanger and next-generation sequencing was attempted in all cases. All six identified cases (four males-two females; three DIA-three DIG) occurred in children <1-year old, were large, cerebral-hemispheric, cystic and solid, and enhancing tumors. Only one case, a DIG with prominent aggregates of neoplastic ganglion cells, showed either BRAF VE1 IHC positivity or mutation by Sanger and next-generation sequencing (rare c. 1799_1800delinsAT; p. V600D). Four of six archival cases were BRAF VE1 IHC negative, but failed mutational sequencing. Five of six classic DIA/DIGs were negative for BRAF mutation; previous series have identified BRAF mutation in two of 18 and one of 14 cases, although all were the more common BRAF V600E. We were unable to find other examples of glial tumors in public databases with this rare BRAF V600D mutation. Identification of BRAF mutational opens the possibility of BRAF-targeted therapies for the subset of DIA/DIG that clinically progress postresection.