Peripheral nerve schwannoma preoperatively diagnosed by sonography: report of three cases and discussion

The preoperative diagnosis of peripheral nerve schwannoma was correctly made by US in 3 patients referred to US because of upper extremity palpable mass. The patients complained of no pain and neurological symptoms, except in two cases where there was painful sensation radiating distally during lesion compression. In all cases, sonography demonstrated a sharply delineated hypoechoic homogenous mass with distal acoustic enhancement. The lesions were noted to be in a direct continuity with the cord-like echogenic structure consistent with a nerve. These features enabled a reliable diagnosis of peripheral nerve tumor, most likely schwannoma, to be made. Following a surgical excision, the diagnosis of schwannoma was confirmed by histopathology in all cases.