# Metastatic extraneural glioblastoma diagnosed with molecular testing

## TL;DR

A rare case of brain cancer spreading outside the nervous system was correctly diagnosed using molecular testing, which was not possible with traditional methods.

## Contribution

This case highlights the importance of next-generation sequencing in diagnosing extraneural glioblastoma metastases.

## Key findings

- Extraneural metastasis of glioblastoma was confirmed through molecular profiling of metastatic lesions.
- Molecular alterations in CDK4, pTERT, PTEN, TP53, and MYC were identified in the metastatic tumor.
- Histology alone was insufficient for diagnosis; molecular testing was essential.

## Abstract

Glioblastoma, the most common malignant brain tumor in adults, is associated with a median overall survival duration of less than 2 years. Extraneural metastases occur in less than 1% of all patients with glioblastoma. The mechanism of extraneural metastasis is unclear. We present a case of extensive extraneural, extraosseous, epidural, and soft-tissue metastasis of glioblastoma. The diagnosis of metastatic glioblastoma was made only after next-generation sequencing (NGS) of the metastatic paraspinal lesions was completed. The CDK4, pTERT, PTEN, and TP53 molecular alterations seen in the initial intracranial glioblastoma were found in the paraspinal tumor, along with the addition of MYC, which is implicated in angiogenesis and epidermal-to-mesenchymal transition. Immunohistochemical stains showed that neoplastic cells were negative for GFAP. In conclusion, this case raises awareness about the role of NGS in the diagnosis of extraneural glioblastoma. This diagnosis was not possible with histology alone and only became evident after molecular profiling of the metastatic lesions and its comparison to the original tumor.

This case raises awareness about the role of next-generation sequencing in the diagnosis of extraneural glioblastoma.