Ancient Schwannoma of Radial Nerve: A Rare Case Report

Abstract

Introduction Schwannoma is a benign tumor of nerve sheath origin. Ancient schwannomas were first described by Ackerman and Taylor in 1951. In the upper limb, the ulnar and median nerves are the primary nerves of flexor surfaces where schwannomas typically arise. The radial nerve is involved in just 7% of peripheral schwannomas. Case Report A 25-year-old male presented to the surgery OPD with a history of forearm swelling for 5 years. On ultrasonography (USG), there was a hypoechoic lesion in the anterior aspect of the forearm. Based on the long duration, clinical examination, and imaging, a diagnosis of benign nerve sheath tumor was made. Excision biopsy was performed, and a globular grey-white tissue piece measuring 2.5x1.5 cm was received in the Department of Pathology. Sections from the globular mass revealed a well-circumscribed tumor with oval to spindle cells randomly arranged within myxoid stroma. There were areas of marked degenerative changes with occasional interspersed hypocellular areas. Immunohistochemistry (IHC) was applied to further confirm the origin of these cells. These cells were positive for vimentin and S-100. The final diagnosis, based on histomorphological features and IHC, was given as ancient schwannoma. Conclusion Ancient schwannomas involving the radial nerve are very rare. They can be confused with malignant peripheral nerve sheath tumors on imaging due to degenerative features and nuclear pleomorphism. Histopathological examination along with IHC is crucial in the diagnosis of these rare tumors. We report the fourth case of an ancient schwannoma in the upper extremity involving the radial nerve.