Subperiosteal Schwannoma of the Humerus: A Case Report and Review of Literature

Abstract

There are numerous conditions that arise from the surface of bones including both neoplastic and non-neoplastic entities. Schwannoma had been reported to be one of those conditions originating from the bone surface with variable proposed theories on it’s origin. We present a unique case of subperiosteal schwannoma arising from the humerus in a 40 years old female with history of painful swelling for two years. Radiograph showed cortically based lytic lesion located in the lateral distal humeral metaphysis with periosteal reaction and cortical scalloping. MRI showed the same juxtacortical lesion with a large extraosseous soft tissue component. It demonstrates intermediate T1 signal intensity and high signal intensity on T2 weighted images with intense enhancement. US guided biopsy showed benign peripheral nerve sheath tumour, consistent with schwannoma. The patient underwent complete rescetion with no complications or documented recurrence till the latest follow-up. In conclusion, subperiosteal schwannoma should be kept in the differential diagnosis in patients presenting with bone surface lesions associated with unexplained vague pain and swelling for a prolonged period of time.