# Post-operative spread of small cell glioblastoma to the subcutaneous tissue via craniotomy defect in a 9-year-old boy: An exceptionally rare case report and review of the literature

## TL;DR

A 9-year-old boy with a rare brain tumor called small cell glioblastoma (scGBM) experienced tumor recurrence as a subcutaneous mass after surgery and radiotherapy, highlighting the aggressive nature and diagnostic challenges of this tumor.

## Contribution

This case report adds to the limited literature on scGBM in children and emphasizes the importance of molecular and immunohistochemical studies for accurate diagnosis.

## Key findings

- The tumor recurred as a subcutaneous mass at the craniotomy site after radiotherapy.
- scGBM was diagnosed using histopathological, immunohistochemical, and molecular studies.
- The case underscores the aggressive behavior and poor prognosis of scGBM in pediatric patients.

## Abstract

Glioblastoma multiforme (GBM), a grade 4 astrocytoma, represents a predominant malignant primary tumor within the central nervous system (CNS) and is known for its dismal prognosis. While extremely uncommon in pediatric cases, the small cell glioblastoma (scGBM) variant poses diagnostic challenges due to overlapping histopathological features with other intracranial tumors.

We present the case of a 9-year-old Persian boy who underwent a craniotomy due to a malignant brain tumor. The histopathological examination, followed by ancillary immunohistochemical and molecular studies, led to the rare diagnosis of scGBM. Following a course of 32-session adjuvant radiotherapy, the tumor recurred with a peculiar manifestation, a subcutaneous mass at the previous surgical site, as a result of recurrent tumor invasion through craniotomy defect.

Small-cell glioblastoma (scGBM) presents aggressive features, often misdiagnosed as other tumors. A rare pediatric occurrence, scGBM requires careful histopathological and molecular evaluations. Treatment aligns with classic GBM protocols, but prognosis is poor, with overall survival ranging from 5 to 23 months.

The case highlights the diagnostic intricacies in distinguishing scGBM from other morphologically similar intracranial tumors, especially in pediatric patients. The report contributes to the limited literature on scGBM in the young population, emphasizing the significance of refined diagnostic approaches for accurate diagnosis and appropriate succeeding treatment for the best patient result.

•This report details a rare presentation of small cell glioblastoma (scGBM) in a 9-year-old boy.•Similar histopathological featuresto other brain tumors underscores the mandatory need for immunohistochemical and molecular studies for definitive diagnosis in such cases.•Post-radiotherapy, the tumor recurred as a subcutaneous mass at the craniotomy site, emphasizing the need for vigilance monitoring and the drastic aggressive nature of scGBM.

This report details a rare presentation of small cell glioblastoma (scGBM) in a 9-year-old boy.

Similar histopathological featuresto other brain tumors underscores the mandatory need for immunohistochemical and molecular studies for definitive diagnosis in such cases.

Post-radiotherapy, the tumor recurred as a subcutaneous mass at the craniotomy site, emphasizing the need for vigilance monitoring and the drastic aggressive nature of scGBM.