Case Report: High-grade diffuse leptomeningeal glioneuronal tumor-MC2 in a 6-year-old child with diagnostic delay and short-term complete radiological response after CEV-based chemotherapy
Abstract
Diffuse leptomeningeal glioneuronal tumor (DLGNT) represents a rare central nervous system neoplasm predominantly observed in pediatric patients. Most cases pursue an indolent clinical course; nevertheless, a small subset demonstrates high-grade histology together with craniospinal dissemination and carries a dismal prognosis. We describe a 6-year-old girl presenting with recurrent vomiting and obstructive hydrocephalus. Initial neuroimaging revealed cerebellar cystic lesions and diffuse leptomeningeal enhancement, which was initially misinterpreted as infectious meningoencephalitis. Tumor biopsy was declined by the patient’s family at initial consultation, and ventriculoperitoneal shunt placement was performed for hydrocephalus relief. One year after shunt surgery, craniospinal magnetic resonance imaging (MRI) documented substantial tumor progression, with corpus callosum infiltration and vertebral body signal abnormalities. Subsequent biopsy established the diagnosis of DLGNT with high-grade histological features, with a Ki-67 proliferation index of approximately 80%. DNA-methylation profiling assigned the tumor to the DLGNT-MC2 molecular subclass. Additional molecular findings included KIAA1549::BRAF gene fusion, 1p deletion, 1q gain, and 17q gain, with an intact 19q and no 1p/19q codeletion. The child received eight cycles of carboplatin, etoposide, and vincristine (CEV) chemotherapy. Nine months after completing treatment, whole-neuroaxis contrast-enhanced MRI (brain and entire spine) showed no residual or recurrent enhancing lesions in either the brain or spine. Neurological function remained stable, and no further seizure episodes occurred. Treatment-related adverse events were confined to grade 2 myelosuppression and mild gastrointestinal intolerance, which were managed by supportive care measures. Our case suggests that risk-adapted CEV chemotherapy may serve as a reasonable upfront therapeutic option for unresectable, aggressive MC2-subtype DLGNT, achieving a short-term complete radiological response. Extended clinical and radiological surveillance is mandatory to validate long-term disease control.
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BibTeX
@article{deng2026case,
title = {{Case Report: High-grade diffuse leptomeningeal glioneuronal tumor-MC2 in a 6-year-old child with diagnostic delay and short-term complete radiological response after CEV-based chemotherapy}},
author = {Wangbin Deng and Guofu Li and Yongkang Zhang},
journal = {Frontiers in Oncology},
year = {2026},
month = nov,
doi = {10.3389/fonc.2026.2015592},
url = {https://www.frontiersin.org/articles/10.3389/fonc.2026.2015592},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Case Report: High-grade diffuse leptomeningeal glioneuronal tumor-MC2 in a 6-year-old child with diagnostic delay and short-term complete radiological response after CEV-based chemotherapy
AU - Wangbin Deng
AU - Guofu Li
AU - Yongkang Zhang
PY - 2026
DA - 2026/11/13
JO - Frontiers in Oncology
DO - 10.3389/fonc.2026.2015592
UR - https://www.frontiersin.org/articles/10.3389/fonc.2026.2015592
AB - Diffuse leptomeningeal glioneuronal tumor (DLGNT) represents a rare central nervous system neoplasm predominantly observed in pediatric patients. Most cases pursue an indolent clinical course; nevertheless, a small subset demonstrates high-grade histology together with craniospinal dissemination and carries a dismal prognosis. We describe a 6-year-old girl presenting with recurrent vomiting and obstructive hydrocephalus. Initial neuroimaging revealed cerebellar cystic lesions and diffuse leptomeningeal enhancement, which was initially misinterpreted as infectious meningoencephalitis. Tumor biopsy was declined by the patient’s family at initial consultation, and ventriculoperitoneal shunt placement was performed for hydrocephalus relief. One year after shunt surgery, craniospinal magnetic resonance imaging (MRI) documented substantial tumor progression, with corpus callosum infiltration and vertebral body signal abnormalities. Subsequent biopsy established the diagnosis of DLGNT with high-grade histological features, with a Ki-67 proliferation index of approximately 80%. DNA-methylation profiling assigned the tumor to the DLGNT-MC2 molecular subclass. Additional molecular findings included KIAA1549::BRAF gene fusion, 1p deletion, 1q gain, and 17q gain, with an intact 19q and no 1p/19q codeletion. The child received eight cycles of carboplatin, etoposide, and vincristine (CEV) chemotherapy. Nine months after completing treatment, whole-neuroaxis contrast-enhanced MRI (brain and entire spine) showed no residual or recurrent enhancing lesions in either the brain or spine. Neurological function remained stable, and no further seizure episodes occurred. Treatment-related adverse events were confined to grade 2 myelosuppression and mild gastrointestinal intolerance, which were managed by supportive care measures. Our case suggests that risk-adapted CEV chemotherapy may serve as a reasonable upfront therapeutic option for unresectable, aggressive MC2-subtype DLGNT, achieving a short-term complete radiological response. Extended clinical and radiological surveillance is mandatory to validate long-term disease control.
SN - 2234-943X
ER -