Case Report
Copyright ©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Clin Cases. Mar 6, 2024; 12(7): 1326-1332
Published online Mar 6, 2024. doi: 10.12998/wjcc.v12.i7.1326
Misdiagnosis of synovial sarcoma - cellular myofibroma with SRF-RELA gene fusion: A case report
Ying Zhou, Yi-Wen Sun, Xiao-Yang Liu, Dan-Hua Shen
Ying Zhou, Yi-Wen Sun, Xiao-Yang Liu, Dan-Hua Shen, Department of Pathology, Peking University People’s Hospital, Beijing 100044, China
Author contributions: Zhou Y and Sun YW designed the research study; Zhou Y, Sun YW and Liu XY performed the research; Zhou Y and Shen DH wrote the manuscript; All authors have read and approved the final manuscript.
Informed consent statement: Written informed consent has been obtained from the patient for publication of this case report.
Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article.
CARE Checklist (2016) statement: The authors have read the CARE Checklist (2016), and the manuscript was prepared and revised according to the CARE Checklist (2016).
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Dan-Hua Shen, MD, Chief Physician, Department of Pathology, Peking University People's Hospital, No. 11 Xizhimen South Street, Beijing 100044, China. shendanhua@pkuph.edu.cn
Received: November 11, 2023
Peer-review started: November 11, 2023
First decision: December 26, 2023
Revised: January 6, 2024
Accepted: January 25, 2024
Article in press: January 25, 2024
Published online: March 6, 2024
Processing time: 110 Days and 22.6 Hours
Abstract
BACKGROUND

Cellular myofibroma is a rare subtype of myofibroma that was first described in 2017. Its diagnosis is often challenging because of its relative rarity, lack of known genetic abnormalities, and expression of muscle markers that can be confused with sarcomas that have myogenic differentiation. Currently, scholars have limited knowledge of this disease, and published cases are few. Further accumulation of diagnostic and treatment experiences is required.

CASE SUMMARY

A 16-year-old girl experienced left upper limb swelling for 3 years. She sought medical attention at a local hospital 10 months ago, where magnetic resonance imaging revealed a 5-cm soft tissue mass. Needle biopsy performed at a local hospital resulted in the diagnosis of a spindle cell soft tissue sarcoma. The patient was referred to our hospital for limb salvage surgery with endoprosthetic replacement. She was initially diagnosed with a synovial sarcoma. Consequently, clinical management with chemotherapy was continued for the malignant sarcoma. Our pathology department also performed fluorescence in situ hybridization for result validation, which returned negative for SS18 gene breaks, indicating that it was not a synovial sarcoma. Next-generation sequencing was used to identify the SRF-RELA rearrangement. The final pathological diagnosis was a cellular/myofibroblastic neoplasm with an SRF-RELA gene fusion. The patient had initially received two courses of chemotherapy; however, chemotherapy was discontinued after the final diagnosis.

CONCLUSION

This case was misdiagnosed because of its rare occurrence, benign biological behavior, and pathological similarity to soft tissue sarcoma.

Keywords: Cellular myofibroma; SRF; RELA; Fusion; Pathology; Case report

Core Tip: Cellular myofibroma (CMF) is a rare subtype of myofibroma that exhibits a broad age distribution, and manifests in diverse anatomical locations, including deep soft tissues and skeletal muscles. Owing to the absence of distinct features, CMF is frequently misdiagnosed. Microscopic examination revealed active mitotic figures (non-pathological), focal areas of necrosis, and occasional infiltrative growth. Next-generation sequencing aids in the accurate pathological diagnosis of CMF by detecting the SRF-RELA gene fusion.