Subfrontal recurrence after cerebellar medulloblastoma resection without local relapse: case-based update

Molecular characterization of sub-frontal recurrent medulloblastomas reveals potential clinical relevance

Background

Single recurrence in the sub-frontal region after cerebellar medulloblastoma (MB) resection is rare and the underlying molecular characteristics have not been specifically addressed.

Methods

We summarized two such cases in our center. All five samples were molecularly profiled for their genome and transcriptome signatures.

Results

The recurrent tumors displayed genomic and transcriptomic divergence. Pathway analysis of recurrent tumors showed functional convergence in metabolism, cancer, neuroactive ligand-receptor interaction, and PI3K-AKT signaling pathways. Notably, the sub-frontal recurrent tumors had a much higher proportion (50-86%) of acquired driver mutations than that reported in other recurrent locations. The acquired putative driver genes in the sub-frontal recurrent tumors functionally enriched for chromatin remodeler-associated genes, such as KDM6B, SPEN, CHD4, and CHD7. Furthermore, the germline mutations of our cases showed a significant functional convergence in focal adhesion, cell adhesion molecules, and ECM-receptor interaction. Evolutionary analysis showed that the recurrence could be derived from a single primary tumor lineage or had an intermediate phylogenetic similarity to the matched primary one.

Conclusion

Rare single sub-frontal recurrent MBs presented specific mutation signatures that might be related to the under-dose radiation. Particular attention should be paid to optimally covering the sub-frontal cribriform plate during postoperative radiotherapy targeting.

Remote Supratentorial Recurrent Medulloblastoma: Case Study and Literature Review

Medulloblastomas comprise 10% of pediatric brain tumors. Subfrontal recurrence is uncommon and has been associated with prone positioning, inadequate irradiation of the cribriform plate area, and hydrocephalus management. We discuss the case report of an 8-year-old boy with subfrontal medulloblastoma recurrence. The literature was reviewed using terms such as “medulloblastoma,” “subfrontal recurrence,” and “child.” Forty-eight cases of subfrontal medulloblastoma recurrence were identified. The mean age at presentation was 12.3 years. Gross total resection was achieved in 44%, most patients received adjuvant radiation therapy, and approximately 25% received chemotherapy. The mean recurrence interval was 2.6 years. The mean number of recurrences per patient was 1.2 and the mean survival period was 3.3 years. Even in the case of meticulous resection and sufficient irradiation, recurrences may still occur. Our case indicates that resection of the recurrent lesion and repeat irradiation may benefit patients with satisfactory short-term results.

Medulloblastoma and esthesioneuroblastoma in a pediatric patient: a co-incidence or result of common genetic anomaly

INTRODUCTION

Medulloblastoma is the commonest embryonal brain tumor in children. Their association with other neuroepithelial brain tumors is less known. Here we discuss a pediatric patient who developed esthesioneuroblastoma 2 years after treatment of medulloblastoma.

MATERIALS AND METHODS

A 12-year-old male presented with features of raised intracranial hypertension, and radiology showed posterior fossa midline lesion. The tumor was excised, and biopsy revealed medulloblastoma (non-WNT non-SHH type). He received chemoradiation. Two years later he presented with loss of vision, and radiology revealed a sinonasal mass with subfrontal extension. Subtotal resection was done, and biopsy showed blue round cell tumor in favor of esthesioneuroblastoma.

RESULT

Parents refused further treatment and the patient died 8months after the second surgery.

CONCLUSION

Mixed embryonal and neuroepithelial brain tumors are rare. These may have a common genetic abnormality. They have an aggressive course and bear a poor prognosis.