AB095. Methylation class infant-type hemispheric glioma with CDKN2A/B deletion: a rare case report.

Background: Gliomas are the most common central nervous system (CNS) tumors in infant but with incidence rate only 1.38 per 100,000. Due to distinctive clinical, histologic, and molecular features, the current World Health Organization (WHO) CNS5 separate gliomas in children from adult as pediatric-type diffuse high-grade and low-grade gliomas. Infant hemispheric gliomas constitute a biologically and clinically distinct subgroup of pediatric-type diffuse high-grade. In this case we present clinical, radiographic, intraoperative, and methylation profiling of the first infant-type hemispheric glioma diagnosed in Indonesia.

Case description: This is a case report of infant operated at Dr. Cipto Mangunkusumo National General Hospital, Jakarta, Indonesia in February 2024. A 6-month-old male infant brought to regional hospital due to head enlargement compared to infant of the same age, head circumference was 50 cm [>2 standard deviation (SD)] with frontal bossing. Brain MRI showed large multi-loculated cystic lesion at left parietooccipital region, which appeared hypointense on T1-weithgted (T1W), hyperintense on T2-weighted (T2W) and fluid-attenuated inversion recovery (FLAIR), with irregular contrast enhancing border. There was isointense lesion on T1W with inhomogeneous contrast enhancement. The largest volume of cystic lesion was 216 cm. Intraoperatively, parietal bone was thinner than usual. The brain was tense, purplish, and non-pulsating, giving the impression of a tumor with indistinct borders with the normal cortex. Dark clear yellowish fluid was spurt after the cortex was incised. Histopathological findings revealed moderate to high cellularity tumor tissue with mitosis, microvascular proliferation, palisading necrosis. In collaboration with German Cancer Research Center (DKFZ), DNA methylation array analysis showed the tumor to match the Infant-type Hemispheric Glioma methylation class (calibrated score 0.94) with deletion of cyclin dependent kinase inhibitor 2A/B (CDKN2A/B).

Conclusions: Methylation class (MC) infant-type hemispheric glioma may present with macrocephaly. On magnetic resonance imaging (MRI) it may appear as large multi-loculated cystic lesion and irregular contrast enhancing border. The key diagnostic criteria for infant-type hemispheric glioma involve combination of clinical, pathological, and molecular feature.