# Unexpected detection of clear cell sarcoma of soft tissue during single-channel endoscopic carpal tunnel release for recurrent carpal tunnel syndrome: a case report with literature review

## TL;DR

A rare case of clear cell sarcoma was unexpectedly found during surgery for carpal tunnel syndrome, highlighting the need for careful exploration in recurrent cases.

## Contribution

This case report highlights the importance of considering neoplastic compression in recurrent carpal tunnel syndrome, especially when imaging is inconclusive.

## Key findings

- A protruding mass identified during surgery was diagnosed as clear cell sarcoma of soft tissue.
- The tumor showed an EWSR1/ATF1 fusion gene but no BRAF V600E mutation.
- Complete symptom relief was achieved after tumor resection and adjuvant therapy.

## Abstract

Carpal tunnel syndrome (CTS) is most commonly idiopathic or associated with wrist strain, while neoplastic compression, a rare etiology, is easily overlooked. This report describes a 50-year-old male patient presenting with numbness in the 1st to 4th fingers of the right hand. Preoperative electromyography confirmed the diagnosis of CTS, but ultrasonography showed no obvious abnormalities. During single-channel endoscopic carpal tunnel release, a protruding mass was identified at the bottom of the carpal tunnel, which was resected and sent for pathological examination. Immunohistochemical and molecular testing results indicated clear cell sarcoma of soft tissue with a maximum diameter of 4 cm. No BRAF gene V600E mutation was detected, but the EWSR1/ATF1 fusion gene was positive. Following tumor resection and multimodal adjuvant therapy, the patient achieved complete relief of numbness and maintained independent daily living activities at the 12-month follow-up, with stable pulmonary disease. This study analyzes the clinical characteristics, diagnosis, and treatment of the case, combined with a literature review. It suggests that neoplastic compression should be suspected in male patients with recurrent CTS, especially when preoperative imaging is negative, and meticulous intraoperative exploration is crucial. Literature analysis shows that wrist tumors are prone to recurrent nerve compression due to anatomical space limitations, and early identification followed by surgical resection is key to improving prognosis.