# An atypical presentation of infiltrative diffuse low-grade glioma in an adolescent: case report

## TL;DR

A 13-year-old boy with an unusual brain tumor showed behavioral issues and sleep problems, not typical neurological symptoms, highlighting the challenge of diagnosing rare pediatric brain tumors.

## Contribution

This paper presents a rare case of an adult-type diffuse low-grade glioma diagnosed in a pediatric patient with a decade-long monitoring period.

## Key findings

- The patient exhibited behavioral and psychiatric symptoms without typical neurological signs.
- MRI showed progressive infiltrative tumor growth over six years before diagnosis.
- Tumor DNA sequencing revealed a canonical IDH1 mutation.

## Abstract

Diffuse low-grade gliomas (dLGG) are rare slow growing brain tumors. Symptoms associated with dLGG typically include seizures, hemiparesis, ataxia, behavioral changes, headaches, and tremors. In this study, we present the case of a thirteen-year-old male admitted to the National Institutes of Health (NIH) Undiagnosed Diseases Program (UDP). To the best of our knowledge, this is one of the only documented cases of an adult-type dLGG diagnosed in a pediatric patient with monitoring of tumor progression for nearly a decade prior to diagnosis.

The patient presented with a history of progressive signal abnormalities on brain magnetic resonance imaging (MRI), refractory to treatment attention deficit hyperactivity disorder (ADHD) and Oppositional Defiant Disorder (ODD), headaches, irritability, and difficulties sleeping. His detailed neurological exam was normal. Following six years of repeated MRI demonstrating increasing infiltrative tumor mass effect throughout gray and white matter, a brain biopsy was performed. The brain biopsy showed white and gray matter with mildly hypercellular areas, and tumor DNA sequencing showed the presence of a canonical IDH1 mutation. A “watch and wait” approach was adopted resulting from discussions between the patient and his family alongside the medical team with repeated quarterly brain MRI to monitor symptoms and tumor growth.

While behavioral and psychiatric changes are common in brain tumor patients, they typically present alongside neurological symptoms which emphasizes the difficulty in diagnosing cases like this patient’s. Low-grade malignancies should be part of the differential diagnosis in cases with progressive multifocal white matter lesions, despite the absence of the typical neurological focal signs.