# Case report: A rare case of malignant solitary fibrous tumor in an adult with an epithelioid pattern in the occipital region

## TL;DR

A rare case of a malignant tumor with a specific genetic fusion was identified in a 59-year-old woman's brain, with no recurrence after surgery.

## Contribution

The identification of a rare NAB2ex7-STAT6 exon15/16 fusion in a malignant solitary fibrous tumor with epithelioid morphology.

## Key findings

- A rare NAB2ex7-STAT6 exon15/16 fusion was detected in a malignant solitary fibrous tumor.
- STAT6 immunohistochemistry showed diffuse and strong positivity in the tumor.
- The patient showed no recurrence after 20 months of follow-up.

## Abstract

We illustrated a rare case of malignant solitary fibrous tumor (MSFT) with epithelioid morphology in the occipital region of a 59-year-old female, in which a rare NAB2ex7-STAT6 exon15/16 double fusion subtype was detected by the Next-generation sequencing (NGS) and STAT6 immunohistochemistry (IHC) was diffusely and strongly positively expressed, without recurrence after 20 months of postoperative follow-up. The morphological and molecular genetic aspects and the differential diagnosis are described, and the relevant literature was assessed in order to broaden our understanding and diagnostic capability of this malignancy.