# A Case of Gastric Atypical Lipomatous Tumor/Well‐Differentiated Liposarcoma With Endoscopic Morphological Changes

## TL;DR

A rare case of gastric atypical lipomatous tumor/well-differentiated liposarcoma is reported, showing unusual endoscopic features and progression over time.

## Contribution

This paper presents a rare gastric manifestation of atypical lipomatous tumor/well-differentiated liposarcoma with progressive endoscopic changes.

## Key findings

- The tumor was composed of fatty tissue and fibrous stroma with nuclear atypia.
- CDK4 and MDM2 positivity and MDM2 amplification confirmed the diagnosis.
- The tumor exhibited progressive morphological changes over several years.

## Abstract

Atypical lipomatous tumor/well‐differentiated liposarcoma is a locally aggressive mesenchymal neoplasm composed of adipocytes and stromal cells. Gastric cases are exceedingly rare, and their malignant potential remains unclear. We report a case of a woman in her 60s who was found to have multiple submucosal tumor‐like lesions of the stomach. Over time, the tumors increased in size, requiring a laparoscopic partial gastrectomy. Histological examination revealed a tumor composed of both fatty tissue and fibrous stroma with nuclear atypia. Immunohistochemistry showed positivity for CDK4 and MDM2, and fluorescence in situ hybridization confirmed MDM2 amplification, leading to a diagnosis of atypical lipomatous tumor/well‐differentiated liposarcoma. This case presented an unusual gastric manifestation, with multiple submucosal tumor‐like lesions on endoscopy and exhibiting progressive morphological changes over several years.