Unexpected ulnar nerve schwannoma. The reasonable risk of misdiagnosis

Peripheral nerve tumors are rare clinical entities that can present with mild symptoms and no neurological deficit. The authors describe one case of asymptomatic schwannoma of the ulnar nerve in a 64-year-old man. The mass was associated with mild and sporadic discomfort due to the mass size; the clinical neurological examination was not conclusive, with Tinel's sign negative; surgery confirmed the nervous origin of the tumor and the histopathologic exam confirmed the diagnosis of schwannoma. These tumors are difficult to diagnose clinically and have often been confused with other benign tumors such as lipomas, hemangiomas, synovial cysts, neurofibromas, etc. Clinical care is important to prevent, during the surgery, the unfortunate resection of the nerve; all too frequently this diagnosis is made intraoperatively or postoperatively with the potential to compromise the outcome of the treatment. An appropriate degree of awareness is necessary for the inclusion of peripheral nerve tumors as a differential diagnosis of an upper extremity mass.