# Rare co-occurrence of gastrointestinal stromal tumors and leiomyomas: A case report and review of the literature

## TL;DR

A rare case shows gastrointestinal stromal tumor and gastric leiomyoma coexisting, suggesting a possible link through BRAFV600E mutations.

## Contribution

The study reports a rare coexistence of GIST and gastric leiomyoma with BRAFV600E mutation, challenging prior assumptions about their independence.

## Key findings

- A single subepithelial lesion contained both GIST and gastric leiomyoma.
- BRAFV600E mutation was detected in the GIST specimen.
- KIT and BRAFV600E genes were simultaneously expressed, challenging prior assumptions.

## Abstract

Gastrointestinal stromal tumors (GISTs) are recognized as the most common neoplasms originating from gastrointestinal mesenchymal tissue. On the other hand, gastric leiomyomas are a common benign neoplasm within the gastrointestinal tract. In general, GISTs are thought to be unrelated to gastric leiomyomas; however, the findings presented in the current study disprove this. The current case report presents a rare case where both GIST and gastric leiomyoma coexisted in a single subepithelial lesion (SEL) at the gastric cardia. Previous studies have confirmed that GIST can originate from smooth muscle cells with a BRAFV600E mutation, which was detected in the present GIST specimen. Notably, simultaneous expression of the KIT and BRAFV600E gene was also observed, challenging the previous assumption that only wild-type GIST would carry the BRAFV600E gene. In conclusion, it is proposed that there may be homology between GISTs and gastric leiomyomas, and the BRAFV600E mutation was the critical trigger. Therefore, the incidence of BRAFV600E might have been underestimated in reality. The present study highlights that clinicians should be aware that GIST and gastric leiomyoma can coexist in the same SEL to avoid misdiagnosis and mistreatment. In the face of the escalating drug resistance rate of GIST, researchers may derive some novel insights from the present findings for GIST treatment and management.