Epithelioid Sarcoma of the Forearm Arising from Perineural Sheath of Median Nerve Mimicking Carpal Tunnel Syndrome

We report here a case of epithelioid sarcoma in the forearm of a 33-year-old male presenting with symptoms and signs of carpal tunnel syndrome originating from the direct involvement of the median nerve. Due to the slow growing of the tumor, the patient noticed the presence of tumor mass in his forearm after several months from the initial onset of the symptoms. Magnetic resonance imaging showed an 8×4 cm mass involving the median nerve in the middle part of the forearm, and histological analysis of the biopsy specimen revealed the diagnosis of epithelioid sarcoma. Radical surgical resection was performed in conjunction with adjuvant chemotherapy. The function of the flexors were restored by the multiple tendon transfers (EIP→FDS; ECRL→FDP; BrR→FPL; EDM→opponens) with superficial cutaneous branch of radial nerve transfer to the resected median nerve. The function of the affected hand showed excellent with the DASH disability/symptom score of 22.5, and both the grasp power and sensory of the median nerve area has recovered up to 50% of the normal side. The patient returned to his original vocation and alive with continuous disease free at 3.5-year follow-up since initial treatment.