# EBV-associated leiomyosarcoma in an immunocompromised child: A unique intracranial case with genomic study

## TL;DR

This paper reports a rare case of EBV-linked brain cancer in an immunocompromised child and emphasizes the importance of detecting EBV in diagnosing such tumors.

## Contribution

The paper presents a unique intracranial case of EBV-associated leiomyosarcoma in a child and highlights the diagnostic importance of EBV detection.

## Key findings

- EBV-associated leiomyosarcomas are rare but more common in immunocompromised individuals.
- In situ hybridization is crucial for confirming EBV presence in undifferentiated smooth muscle tumors.
- Complete surgical excision is typically the primary treatment for these tumors.

## Abstract

Epstein-Barr virus (EBV) is a common virus infecting more than 90 % of the adult population, typically without symptoms. While most infections remain asymptomatic, EBV is associated with over 200,000 new cancer cases annually. It is linked to several malignancies, including leiomyosarcoma (LS) in immunocompromised patients, a rare occurrence with fewer than 100 new cases per year globally. This report highlights the case of an EBV-associated intracranial leiomyosarcoma in a 4-year-old immunodeficient child.

A 4-year-old girl with a history of primary immune deficiency and multiple infections presented with febrile dyspnea. Imaging revealed a right temporo-parietal brain mass, which increased in size over 50 days. Surgical excision was performed, and histological examination showed a tumor with smooth muscle cell characteristics. Immunohistochemical analysis was positive for vimentin and CD99, while EBV genome presence was confirmed by in situ hybridization. The final diagnosis was EBV-associated malignant smooth muscle tumor. The postoperative course was favorable, and chemotherapy was not indicated.

Leiomyosarcoma is extremely rare in immunocompetent children but more common in immunocompromised individuals, where EBV infection plays a significant role in tumor development. Although EBV-related leiomyosarcomas occur more frequently in immunodeficient children, intracranial cases are exceptionally rare. These tumors are often challenging to diagnose due to their undifferentiated appearance. The detection of EBV DNA using in situ hybridization is crucial for confirming the diagnosis. While EBV-associated leiomyosarcomas generally respond well to therapy, the optimal treatment remains unclear, with surgery and radiotherapy being the primary approaches.

EBV-associated smooth muscle tumors are rare but increasing in incidence among immunocompromised patients. Early recognition of EBV infection in smooth muscle tumors, especially in children with immune deficiencies, is vital for diagnosis. Histological and molecular examination, including in situ hybridization, is essential to confirm the presence of EBV. Treatment typically involves complete surgical excision, with chemotherapy's role still uncertain.

•EBV-associated SMTs make up 3-17% of cancers in immunocompromised individuals, but less than 100 new EBV-LS cases occur annually.•Diagnosing EBV-SMTs is challenging due to their undifferentiated appearance and difficulty distinguishing benign from malignant forms.•In situ hybridization with EBER identifies the EBV genome in tumor cells.•Immunosuppression, young age, and smooth muscle appearance should prompt pathologists to perform in situ hybridization for EBV detection.

EBV-associated SMTs make up 3-17% of cancers in immunocompromised individuals, but less than 100 new EBV-LS cases occur annually.

Diagnosing EBV-SMTs is challenging due to their undifferentiated appearance and difficulty distinguishing benign from malignant forms.

In situ hybridization with EBER identifies the EBV genome in tumor cells.

Immunosuppression, young age, and smooth muscle appearance should prompt pathologists to perform in situ hybridization for EBV detection.