# KIAA1549-BRAF Gene Fusion Spindle Cell Sarcoma With Infantile Fibrosarcoma-Like Pattern in a Pediatric Patient: A Case Report

## TL;DR

A three-year-old girl was diagnosed with a rare childhood sarcoma involving a KIAA1549-BRAF gene fusion, which resembles infantile fibrosarcoma and responded well to treatment.

## Contribution

The case highlights the diagnostic importance of molecular testing for KIAA1549-BRAF fusion in tumors resembling infantile fibrosarcoma.

## Key findings

- The tumor showed a favorable outcome three years after surgery.
- Molecular testing was essential for accurate diagnosis due to morphological similarity to infantile fibrosarcoma.
- The KIAA1549-BRAF fusion suggests potential for targeted therapies in refractory cases.

## Abstract

Spindle cell sarcoma with KIAA1549-BRAF fusion is a type of childhood sarcoma that closely resembles infantile fibrosarcoma by morphologic criteria and harbors molecular alteration other than the ETV6-NTRK3 fusion gene. This neoplasm was diagnostically challenging without molecular tests, including next-generation sequencing. The discovery of BRAF translocation in this tumor contributes to the promise of the clinical implication of selecting new therapeutic options for the treatment of progressive diseases that are refractory to conventional chemotherapy. Here we present the case of a three-year-old girl who was diagnosed with spindle cell sarcoma with KIAA1549-BRAF fusion gene and had a favorable outcome three years after surgery.