Tumors and tumor-like lesions mimicking carpal tunnel syndrome

Tumors and tumor-like lesions in or around the median nerve are uncommon causes of carpal tunnel syndrome (CTS). The purpose of the present study is to highlight the diagnostic approach and point out the profile of patients with CTS and potential underlying pathology.

Twenty-eight patients with 32 affected hands had CTS correlated to a mass in or around the nerve. In 20 hands a palpable mass was present. Diagnostic workup included nerve conduction studies, ultrasound and/or MRI. Pre- and postoperative examination included two-point discrimination (2PD), grip strength, visual analogue scale (for pain) (VAS) and disabilities of the arm, shoulder and hand (DASH) scores.

Twelve of 28 patients were young (range 9-38 years) and 10 were male. Nerve compression was due to 27 extraneural lesions (8 abnormal muscles, 5 lipomas, 7 tenosynovitis, 4 vascular tumors, 2 ganglia, 1 Dupuytren's fibromatosis) and five intraneural tumors (three schwannomas, one neurofibroma, one sarcoma). Nerve decompression and excision of extraneural lesions were performed in all cases whereas in intraneural tumors, decompression was followed by excision in most cases and nerve grafting in one. Mean follow-up was 22 months (12-105 months). Extraneural masses were associated with a better outcome than nerve tumors. The mean postoperative VAS/DASH scores were 0.3/16.2 in extraneural lesions and 2.5/22 in intraneural lesions. The 2PD improved gradually in all patients (mean pre- and postoperative 12 and 5 mm). The mean grip strength increased from 28 to 31.3 kg postoperatively.

Although rare, the surgeon should include in the differential diagnosis of CTS the unusual cause of tumors and tumor-like lesions, especially when the patients' profile is not typical (young, male, no repetitive stress or manual labor). In addition, the presence of a palpable mass at the distal forearm or palm dictates the need for imaging studies. The extent, location and aggressiveness of the mass will determine the approach and type of procedure.