# Malignant perineurioma derived from the retroperitoneum with an aggressive clinical course: a case report

## TL;DR

A rare case of aggressive malignant perineurioma in the retroperitoneum is reported, highlighting the challenges in treatment and the importance of genetic findings.

## Contribution

This case report provides insights into the clinical behavior and genetic profile of a rare retroperitoneal malignant perineurioma.

## Key findings

- The patient had a large hemorrhagic tumor in the retroperitoneum with vena cava obstruction.
- Histopathological and immunohistochemical analysis confirmed the diagnosis of malignant perineurioma.
- An NF2 mutation was identified, suggesting a potential therapeutic target.

## Abstract

Malignant perineurioma is a rare malignant counterpart of perineurioma derived from perineural cells. Resection is the primary option for the treatment of malignant perineuriomas; however, patients often develop recurrence after resection, and effective treatment for advanced or recurrent lesions needs to be established. This report describes a 51-year-old female with a rare malignant perineurioma in the retroperitoneum, which contributing valuable insights to the literature.

The patient presented with abdominal distension and the imaging work-up revealed a huge hemorrhagic tumor in the retroperitoneum and obstruction of inferior vena cava by the tumor. The patient underwent surgery retrieving the tumor combined with left hemiliver and retrohepatic vena cava, which confirmed the diagnosis of a malignant perineurioma based on histopathological and immunohistochemical examination. Cancer gene panel testing identified mutations in NF2. Radiotherapy was administered for peritoneal dissemination 2 months after surgery, and the patient died from disease progression 6 months after surgery.

This rare case highlights the challenges in managing retroperitoneal malignant perineuriomas. The aggressive characteristics and limited treatment options for advanced malignant perineuriomas underscore the need for understanding the pathogenesis and developing effective systemic therapies. The identification of an NF2 mutation provides significant insights into potential therapeutic target.