Related Experiment Video
Updated: May 7, 2026
08:57
Author Spotlight: Genetically Engineered Mouse Models and Pathological Characterization of Neurofibromatosis Type 1 Associated Tumors
Published on: May 17, 2024
3.1K
Extraskeletal Myxoid Chondrosarcoma Mimicking Myoepithelial Tumor
Bowen Jiang1, Masatake Matsuoka1, Kanako C Hatanaka2,3
1Department of Orthopaedic Surgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Hokkaido, Japan, hokudai.ac.jp.
Case Reports in Pathology
|May 6, 2026
Summary
Extraskeletal myxoid chondrosarcoma (EMC) can mimic other tumors, posing diagnostic challenges. Molecular analysis, like RNA sequencing, is crucial for accurate EMC diagnosis when histology and immunohistochemistry are inconclusive.
Area of Science:
- Oncology
- Pathology
- Genetics
Background:
- Extraskeletal myxoid chondrosarcoma (EMC) is a rare soft tissue sarcoma with characteristic features but variable histology.
- Diagnostic challenges arise due to histologic variability and immunophenotypic overlap with other myxoid tumors.
- Myoepithelial markers can be expressed in EMC, potentially leading to misdiagnosis.
Purpose of the Study:
- To report a case of extraskeletal myxoid chondrosarcoma (EMC) with challenging diagnostic features.
- To highlight the utility of molecular analysis in confirming EMC diagnosis when conventional methods are insufficient.
- To demonstrate EMC's potential to mimic myoepithelial tumors.
Main Methods:
- Histopathological examination of a tumor sample from the left knee.
- Immunohistochemical staining for myoepithelial and other relevant markers.
- Targeted RNA sequencing on formalin-fixed, paraffin-embedded tissue.
Main Results:
- The tumor exhibited abundant myxoid stroma, lace-like cellular arrangements, and focal epithelioid morphology.
- Immunohistochemistry showed positivity for myoepithelial markers but negativity for cytokeratin and SOX10.
- Targeted RNA sequencing identified a TAF15::NR4A3 fusion transcript, confirming the diagnosis of EMC.
Conclusions:
- Extraskeletal myxoid chondrosarcoma can present with features mimicking myoepithelial tumors.
- Histologic and immunohistochemical findings alone may be inconclusive for EMC diagnosis.
- Molecular analysis, specifically RNA sequencing, is a valuable tool for diagnosing challenging EMC cases.
