# Primary extraskeletal osteosarcoma of the esophagus with PPM1D-BCAS3 fusion: a case report and literature review

## TL;DR

A rare case of esophageal extraskeletal osteosarcoma with a specific genetic fusion is reported, highlighting the importance of accurate diagnosis and treatment.

## Contribution

This is the first reported case of esophageal extraskeletal osteosarcoma with PPM1D-BCAS3 fusion treated via endoscopic submucosal dissection.

## Key findings

- The patient was diagnosed with primary extraskeletal osteosarcoma of the esophagus confirmed via histopathology.
- The tumor exhibited a PPM1D-BCAS3 fusion, a novel finding in this rare condition.
- The patient experienced recurrence and metastases despite initial treatment without adjuvant therapy.

## Abstract

Extraskeletal osteosarcoma (ESOS), a malignant soft tissue neoplasm characterized by the presence of osteoid or cartilage matrix, arises without bone involvement. ESOS within the esophagus is particularly rare. This study reported a case of esophageal ESOS with PPM1D-BCAS3 fusion, offering an analysis of its clinicopathological features and a comprehensive literature review aimed at advancing the diagnostic understanding of clinical pathologists.

A 76-year-old male presented with a 2-month history of subxiphoid pain and dysphagia. Chest computed tomography CT revealed irregular mid-esophageal wall thickening and luminal stenosis, raising suspicion for mid-esophageal carcinoma. Painless endoscopic ultrasonography detected a hypoechoic intraluminal esophageal mass. Endoscopic submucosal dissection (ESD) and histopathological analysis confirmed primary ESOS of the mid-esophagus. No adjuvant therapy was administered postoperatively. However, the patient experienced a recurrence with multiple metastases 9-months later.

The diagnosis of esophageal ESOS, a condition of exceptional rarity, necessitates an integrative evaluation that encompasses clinical history, imaging modalities, and histopathological analysis, with a critical distinction from metastatic osteosarcoma and carcinosarcoma. This study presented the first case of esophageal ESOS with PPM1D-BCAS3 fusion treated via ESD, providing a significant point of reference for clinicians and pathologists. The management of ESOS demands vigilant monitoring and precise follow-up care.